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AIMS: This study aimed to compare the clinical effectiveness of intramedullary nailing (IMN), percutaneous external plate fixation (PEPF), and re-applied external fixation (REF) in the treatment of refracture at the consolidated docking site following the removal of external fixation in patients with tibial defects who had previously undergone the Ilizarov bone transport technique. METHODS: A retrospective review was performed on patients who received IMN, PEPF, or REF for refracture at the consolidated docking site subsequent to the removal of external fixation. A collection of data was made regarding the following parameters: age, gender, defect size, treatment methods, external fixation time (EFT), external fixation index (EFI), time of refracture (TOR) subsequent to fixation removal, and docking reunion time (DRT). Bone and functional outcomes were evaluated by the Association for the Study and Application of the Method of Ilizarov (ASAMI) scoring system and the Lower Extremity Functional Scale (LEFS) questionnaire. RESULTS: The study included 14 males and 5 females with an average age of 38.1 ± 8.9 years (range, 26 to 55 years). Etiologies included post-traumatic osteomyelitis in 11 cases and post-traumatic bone loss in 8 cases. The median bone defect was 5.11 ± 0.87 cm (range, 3.8 to 6.8 cm). Following docking site refracture, 6 cases were treated with IMN, 8 with PEPF, and 5 with REF. All patients achieved both satisfactory bone union and functional outcomes, and there was no significant difference in preoperative baseline data or postoperative outcomes among the three groups. CONCLUSION: IMN, PEPF, and REF were all demonstrated favorable postoperative bone and functional outcomes, suggesting their reliability as treatment options for managing docking site refracture following external fixation removal.

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PURPOSE: Although bone transport is a well-recognised technique to address segmental bone defects, optimal management of docking sites is not absolutely determined. Some surgeons routinely intervene in all cases, and others prefer to observe and intervene only if spontaneous union does not occur. Primary aim of the study was to compare rates of docking site union between patients who underwent routine docking site intervention and those who did not. METHODS: A systematic literature review using the keywords "bone transport", "docking", "tibia", and "femur" was performed in PubMed using PRISMA guidelines. Studies published in English from January 2000 to August 2022 were included and assessed independently by two reviewers. Pooled analysis was undertaken dividing patients into two groups: those managed by routine intervention and those initially observed. RESULTS: Twenty-three clinical studies met the eligibility criteria for pooled analysis, including 1153 patients, 407 in the routine intervention and 746 in the observed group. The rate of union after initial treatment was 90% in the routine intervention group and 66% in the observed group (p < 0.0001). Overall union rates at the end of treatment were similar at 99% in both groups. Patients in the observed group required an average of 2.2 procedures to achieve union overall compared with 3.8 in the routine intervention group. Time in frame was similar between groups. CONCLUSION: Based on the current literature, routine docking site interventions cannot be recommended, since this may lead to unnecessary interventions in two thirds of patients. Timely selective intervention in those at high risk or after a defined period of observation would appear to be a logical approach.

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BACKGROUND: Treating long bone defects of the extremities caused by trauma, infection, tumours, and nonunion has been challenging for clinical orthopaedic surgeons. Bone transport techniques have the potential to treat bone defects. However, inevitable docking site complications related to bone transport techniques have been reported in many studies. The purpose of this study was to investigate the risk factors associated with docking site complications in patients who underwent the Ilizarov bone transport technique for the treatment of tibial bone defects. METHODS: This retrospective study included 103 patients who underwent bone transport for the treatment of large bone defects in the tibia from October 2012 to October 2019. Patient demographic data, complications and clinical outcomes after a minimum of 2 years of follow-up were collected and retrospectively analysed. Additionally, univariate analysis and logistic regression analysis were used to analyse the factors that may affect the development of docking site complications in patients with tibial bone defects treated with the Ilizarov bone transport technique. The clinical outcomes were evaluated using the Association for the Study and Application of the Ilizarov criteria (ASAMI) at the last clinical follow-up. RESULTS: All 103 patients with an average follow-up of 27.5 months. The docking site complications rate per patient was 0.53, and delayed union occurred in 22 cases (21.4%), axial deviation occurred in 19 cases (18.4%) and soft tissue incarceration occurred in 10 cases (9.7%). According to the results of the logistic regression analysis, the bone defect length (P = 0.001, OR = 1.976), and bone defect of distal 1/3 (P = 0.01, OR = 1.976) were significantly correlated with delayed union. Bone defect length (P < 0.001, OR = 1.981) and external fixation time (P = 0.012, OR = 1.017) were significantly correlated with axial deviation. Soft tissue defects (P = 0.047, OR = 6.766) and the number of previous operations (P = 0.001, OR = 2.920) were significantly correlated with soft tissue incarceration. The ASAMI bone score at the last follow-up showed a rate of excellent and good bone results of 95.1% and a rate of excellent functional results of 90.3%. CONCLUSION: The Ilizarov bone transport technique is a practical and effective method for the treatment of tibial bone defects. However, the incidence of complications at the docking site is high, of which bone defect length, external fixation time, the number of previous operations, soft tissue defects and the bone defect of distal 1/3 are statistically significantly associated with the occurrence of docking site complications.

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Extracellular signal-regulated kinase (ERK) is the culmination of a mitogen-activated protein kinase cascade that regulates cellular processes like proliferation, migration, and survival. Consequently, abnormal ERK signaling often plays a role in the tumorigenesis and metastasis of numerous cancers. ERK inhibition is a sought-after treatment for cancers, especially since clinically approved drugs that target signaling upstream of ERK often induce acquired resistance. Furthermore, the ERK2 isoform may have a differential role in various cancers from the other canonical isoform, ERK1. We demonstrate that small molecules can inhibit ERK2 catalytic and noncatalytic functions by binding to the D-recruitment site (DRS), a protein-protein interaction site distal to the enzyme active site. Using a fluorescence anisotropy-based high-throughput screening, we identify compounds that bind to the DRS and exhibit dose-dependent inhibition of ERK2 activity and ERK2 phosphorylation. We characterize the dose-dependent potency of ERK2 inhibitors using fluorescence anisotropy-based binding assays, fluorescence-based ERK2 substrate phosphorylation assays, and in vitro ERK2 activation assays. In our example, the binding of a DRS inhibitor can be prevented by mutating the DRS residue Cys-159 to serine, indicating that this residue is essential for the interaction. Resulting inhibitors from this process can be assessed in cellular and in vivo experiments for inhibition of ERK signaling and can be evaluated as potential cancer drugs.

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OBJECTIVE: To study the effect of freshening technique on docking site in tibial bone transport management. METHODS: Retrospective cohort study was conducted about the effect of freshening technique on docking site in 20 cases(15 males and 5 females) treated with tibial bone transport from January of 2014 to December of 2019. The age of patients ranged from 19 to 62 years old, with an average of (42.3±11.5)years old. Seven patients had infectious bone defect and 13 patients had non-infectious. Application of freshening technique immediately after docking included resection of invaginated skin or soft tissue, removal of closed sclerotic bone, re-apposition, increasing the contact, acute compression of freshened docking site and grafting from adjacent medullary or bone debris, followed by post-operative gradual compression. RESULTS: The amount of segmented bone defect ranged from 5 to 15 cm, with an average of(9.2±2.9) cm. Time required from osteotomy to contact of butt end ranged from 26 to 243 days, with an average of(109.1±51.1) days. The duration needed from 3 to 7 months with an average of(3.7±1.1) months before reaching radiological healing criterion in docking site. Fourteen out of 15 concurrent fibular osteotomy were united. Consolidation time for distracted callus ranged from 5 to 28 months, with an average of (15.0±6.5) months. Bone healing index(BHI) ranged from 0.8 to 2.8 months/cm, with an average of (1.6±0.5) months. One surgical site infection (5%) in tibial was noted. No refractures were found in follow-up ranged from 12 to 73 months, with an average of(37.6±20.3) months after fixator removal. CONCLUSION: Freshening technique immediately after docking had advantages of the shorter healing time, avoidance of refracture, and independance of necessity for remote autograft harvest.

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The LIR motif-docking site (LDS) of Atg8/LC3 proteins is essential for the binding of LC3-interacting region (LIR)-containing proteins and their subsequent degradation by macroautophagy/autophagy. In our recent study, we created a mutated LDS site in Atg8a, the <i>Drosophila</i> homolog of Atg8/LC3 and found that LDS mutants accumulate known autophagy substrates and have reduced lifespan. We also conducted quantitative proteomics analyses and identified several proteins that are enriched in the LDS mutants, including Gmap (Golgi microtubule-associated protein). Gmap contains a LIR motif and accumulates in LDS mutants. We showed that Gmap and Atg8a interact in a LIR-LDS dependent manner and that the Golgi size and morphology are altered in Atg8a-LDS and Gmap-LIR motif mutants. Our findings highlight a role for Gmap in the regulation of Golgiphagy.

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Selective autophagy receptors and adapters contain short linear motifs called LIR motifs (LC3-interacting region), which are required for the interaction with the Atg8-family proteins. LIR motifs bind to the hydrophobic pockets of the LIR motif docking site (LDS) of the respective Atg8-family proteins. The physiological significance of LDS docking sites has not been clarified in vivo. Here, we show that Atg8a-LDS mutant Drosophila flies accumulate autophagy substrates and have reduced lifespan. Using quantitative proteomics to identify the proteins that accumulate in Atg8a-LDS mutants, we identify the cis-Golgi protein GMAP (Golgi microtubule-associated protein) as a LIR motif-containing protein that interacts with Atg8a. GMAP LIR mutant flies exhibit accumulation of Golgi markers and elongated Golgi morphology. Our data suggest that GMAP mediates the turnover of Golgi by selective autophagy to regulate its morphology and size via its LIR motif-mediated interaction with Atg8a.

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Mitogen-activated protein kinases (MAPKs) form tightly controlled signaling cascades that play essential roles in plant growth, development, and defense response. However, the molecular mechanisms underlying MAPK cascades are still very elusive, largely because of our poor understanding of how they relay the signals. The MAPK cascade is composed of MAPK, MAPKK, and MAPKKK. They transfer signals through the phosphorylation of MAPKKK, MAPKK, and MAPK in turn. MAPKs are organized into a complex network for efficient transmission of specific stimuli. This review summarizes the research progress in recent years on the classification and functions of MAPK cascades under various conditions in plants, especially the research status and general methods available for identifying MAPK substrates, and provides suggestions for future research directions.

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Membrane proteins are involved in many aspects of cellular biology; for example, they regulate how cells interact with their environment, so such proteins are important drug targets. The rapid advancement in the field of immune effector cell therapy has been expanding the horizons of synthetic membrane receptors in the areas of cell-based immunotherapy and cellular medicine. However, the investigation of membrane proteins, which are key constituents of cells, is hampered by the difficulty and complexity of their in vitro synthesis, which is of unpredictable yield. Cell-free synthesis is herein employed to unravel the impact of the expression construct on gene transcription and translation, without the complex regulatory mechanisms of cellular systems. Through the systematic design of plasmids in the immediacy of the start of the target gene, it was possible to identify translation initiation and the conformation of mRNA as the main factors governing the cell-free expression efficiency of the human voltage-dependent anion channel (VDAC), which is a relevant membrane protein in drug-based therapy. A simple translation initiation model was developed to quantitatively assess the expression potential for the designed constructs. A scoring function that quantifies the feasibility of the formation of the translation initiation complex through the ribosome-mRNA hybridization energy and the accessibility of the mRNA segment binding to the ribosome is proposed. The scoring function enables one to optimize plasmid sequences and semi-quantitatively predict protein expression efficiencies. This scoring function is publicly available as webservice XenoExpressO at University of Vienna, Austria.

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Despite its potent anti-amyloid properties, the utility of curcumin (Cur) for the treatment of Alzheimer's disease (AD) is limited due to its low bioavailability. Tetrahydrocurcumin (THC), a more stable metabolite has been found in Cur-treated tissues. We compared the anti-amyloid and neuroprotective properties of curcumin, bisdemethoxycurcumin (BDMC), demethoxycurcumin (DMC) and THC using molecular docking/dynamics, in-silico and in vitro studies. We measured the binding affinity, H-bonding capabilities of these compounds with amyloid beta protein (Aß). Dot blot assays, photo-induced cross linking of unmodified protein (PICUP) and transmission electron microscopy (TEM) were performed to monitor the Aß aggregation inhibition using these compounds. Neuroprotective effects of these derivatives were evaluated in N2a, CHO and SH-SY5Y cells using Aß42 (10 µM) as a toxin. Finally, Aß-binding capabilities were compared in the brain tissue derived from the 5× FAD mouse model of AD. We observed that THC had similar binding capability and Aß aggregation inhibition such as keto/enol Cur and it was greater than BDMC and DMC. All these derivatives showed a similar degree of neuroprotection in vitro and labeled Aß-plaques ex vivo. Overall, ECur and THC showed greater anti-amyloid properties than other derivatives. Therefore, THC, a more stable and bioavailable metabolite may provide greater therapeutic efficacy in AD than other turmeric derivatives.

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OBJECTIVE: To investigate the efficiency of internal fixation with bone grafting after bone transport for treatment in large-segment bone defects of the lower-limbs. METHODS: This prospective study recruited 100 patients with lower limb tibial segmental bone defects, and based on a random number table they were divided into a control group (n=50, simple bone transport surgery) or an observation group (n=50, internal fixation with bone grafting at docking site after bone transport). The fracture healing time, bone healing index, external fixation time in both groups were compared. The knee function, joint range of motion, and the function of the ankle and hindfoot before and after surgery were also analyzed and compared between the two groups respectively, as well as the rate of complications in both groups was calculated. RESULTS: Compared with the preoperative condition of patients, the Lysholm knee scale, ROM score, and AHS scores of patients in the two groups were significantly increased 10 months after surgery, moreover, those scores of the observation group were higher than that of the control group (P<0.05). The fracture healing time and external fixation time of patients were significantly declined in the observation group when compared to the control group, additionally, the bone healing index was also reduced significantly (P<0.05). When compared with patients in the control group, the ratios of bone healing and lower-limb functional recovery of patients in the observation group were significantly higher while the total complication incidence was decreased remarkably (P<0.05). CONCLUSION: Internal fixation with bone grafting after bone transport can promote fracture healing, improve joint function, and reduce complications during treatment for a large segmental bone defects in the lower limbs.

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Three isostructural covalent organic frameworks (COFs) with either methoxyl, hydroxyl, or both groups on the channel wall, are synthesized and served as metal-free heterogeneous catalysts for chemical fixation of CO2 . Among them, the COF decorated with both hydroxyl and methoxyl groups named OMe-OH-TPBP-COF exhibits the highest catalytic activity and efficiency for CO2 cycloaddition under mild conditions.

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Mitogen-activated protein kinase (MAPK) regulation of cAMP-specific phosphodiesterase function has been demonstrated in mammalian cells and suspected to occur in other eukaryotes. Epistasis analysis in the soil amoeba Dictyostelium discoideum suggests the atypical MAPK Erk2 downregulates the function of the cAMP-specific phosphodiesterase RegA to regulate progression of the developmental life cycle. A putative MAPK docking motif located near a predicted MAPK phosphorylation site was characterized for contributions to RegA function and binding to Erk2 because a similar docking motif has been previously characterized in the mammalian PDE4D phosphodiesterase. The overexpression of RegA with alterations to this docking motif (RegAD-) restored RegA function to regA- cells based on developmental phenotypes, but low-level expression of RegAD- from the endogenous regA promoter failed to rescue wild-type morphogenesis. Co-immunoprecipitation analysis indicated that Erk2 associates with both RegA and RegAD-, suggesting the docking motif is not required for this association. Epistasis analysis between regA and the only other Dictyostelium MAPK, erk1, suggests Erk1 and RegA can function in different pathways but that some erk1- phenotypes may require cAMP signalling. These results imply that MAPK downregulation of RegA in Dictyostelium is accomplished through a different mechanism than MAPK regulation of cAMP-specific phosphodiesterases in mammalian cells and that the regulation in Dictyostelium does not require a proximal MAPK docking motif.

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BACKGROUND: Ilizarov technique has obvious advantages in the treatment of tibial bone defect and can be used to treat various types of tibial bone defect. However, there are still many shortcomings in this technology, which need to be solved urgently. OBJECTIVE: To review the advantages, shortcomings and improvement strategies of Ilizarov technique in the treatment of tibia bone defect. METHODS: PubMed, CNKI and Wanfang databases from 1971 to 2019 were retrieved with the key words of “bone defect, bone transport, accordion maneuver, ultrasonography, energy spectrum CT, pin site infection” in English and Chinese, respectively. Totally 57 eligible articles were included to systematically summarize the advantages, shortcomings and improvement strategies of Ilizarov technique in the treatment of tibia bone defect. RESULTS AND CONCLUSION: (1) Ilizarov technology has obvious advantages in the treatment of the tibia bone defect, combined with soft tissue injury, infection and deformity of the tibia bone defect. (2) New disinfectants, accordion technology, color Doppler ultrasound and energy spectrum CT are effective treatment methods for complications of bone transport technology, such as pin site infection, poor mineralization of new bone in the transfer area, and difficulty in healing at the docking site. These methods can reduce the incidence of complications. (3) It is still necessary to improve the existing treatment techniques or choose new methods to further reduce the incidence of complications.

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Due to their sedentary lifestyle, plants are constantly exposed to different stress stimuli. Stress comes in variety of forms where factors like radiation, free radicals, "replication errors, polymerase slippage", and chemical mutagens result in genotoxic or cytotoxic damage. In order to face "the base oxidation or DNA replication stress", plants have developed many sophisticated mechanisms. One of them is the DNA mismatch repair (MMR) pathway. The main part of the MMR is the MutS homologue (MSH) protein family. The genome of Arabidopsis thaliana encodes at least seven homologues of the MSH family: AtMSH1, AtMSH2, AtMSH3, AtMSH4, AtMSH5, AtMSH6, and AtMSH7. Despite their importance, the functions of AtMSH homologs have not been investigated. In this work, bioinformatics tools were used to obtain a better understanding of MSH-mediated DNA repair mechanisms in Arabidopsis thaliana and to understand the additional biological roles of AtMSH family members. In silico analysis, including phylogeny tracking, prediction of 3D structure, interactome analysis, and docking site prediction, suggested interactions with proteins were important for physiological development of A. thaliana. The MSH homologs extensively interacted with both TIL1 and TIL2 (DNA polymerase epsilon catalytic subunit), proteins involved in cell fate determination during plant embryogenesis and involved in flowering time repression. Additionally, interactions with the RECQ protein family (helicase enzymes) and proteins of nucleotide excision repair pathway were detected. Taken together, the results presented here confirm the important role of AtMSH proteins in mismatch repair and suggest important new physiological roles.

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Febrile-range hyperthermia worsens and hypothermia mitigates lung injury, and temperature dependence of lung injury is blunted by inhibitors of p38 mitogen-activated protein kinase (MAPK). Of the two predominant p38 isoforms, p38α is proinflammatory and p38ß is cytoprotective. Here, we analyzed the temperature dependence of p38 MAPK activation, substrate interaction, and tertiary structure. Incubating HeLa cells at 39.5 °C stimulated modest p38 activation, but did not alter tumor necrosis factor-α (TNFα)-induced p38 activation. In in vitro kinase assays containing activated p38α and MAPK-activated kinase-2 (MK2), MK2 phosphorylation was 14.5-fold greater at 39.5 °C than at 33 °C. By comparison, we observed only 3.1- and 1.9-fold differences for activating transcription factor-2 (ATF2) and signal transducer and activator of transcription-1α (STAT1α) and a 7.7-fold difference for p38ß phosphorylation of MK2. The temperature dependence of p38α:substrate binding affinity, as measured by surface plasmon resonance, paralleled substrate phosphorylation. Hydrogen-deuterium exchange MS (HDX-MS) of p38α performed at 33, 37, and 39.5 °C indicated temperature-dependent conformational changes in an α helix near the common docking and glutamate:aspartate substrate-binding domains at the known binding site for MK2. In contrast, HDX-MS analysis of p38ß did not detect significant temperature-dependent conformational changes in this region. We observed no conformational changes in the catalytic domain of either isoform and no corresponding temperature dependence in the C-terminal p38α-interacting region of MK2. Because MK2 participates in the pathogenesis of lung injury, the observed changes in the structure and function of proinflammatory p38α may contribute to the temperature dependence of acute lung injury.

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Extracellular signal-regulated kinase 1/2 (ERK1/2) constitute a point of convergence for complex signaling events that regulate essential cellular processes, including proliferation and survival. As such, dysregulation of the ERK signaling pathway is prevalent in many cancers. In the case of BRAF-V600E mutant melanoma, ERK inhibition has emerged as a viable clinical approach to abrogate signaling through the ERK pathway, even in cases where MEK and Raf inhibitor treatments fail to induce tumor regression due to resistance mechanisms. Several ERK inhibitors that target the active site of ERK have reached clinical trials, however, many critical ERK interactions occur at other potentially druggable sites on the protein. Here we discuss the role of ERK signaling in cell fate, in driving melanoma, and in resistance mechanisms to current BRAF-V600E melanoma treatments. We explore targeting ERK via a distinct site of protein-protein interaction, known as the D-recruitment site (DRS), as an alternative or supplementary mode of ERK pathway inhibition in BRAF-V600E melanoma. Targeting the DRS with inhibitors in melanoma has the potential to not only disrupt the catalytic apparatus of ERK but also its noncatalytic functions, which have significant impacts on spatiotemporal signaling dynamics and cell fate.

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During autophagy, vesicle dynamics and cargo recruitment are driven by numerous adaptors and receptors that become tethered to the phagophore through interactions with lipidated ATG8/LC3 decorating the expanding membrane. Most currently described ATG8-binding proteins exploit a well-defined ATG8-interacting motif (AIM, or LC3-interacting region [LIR]) that contacts a hydrophobic patch on ATG8 known as the LIR/AIM docking site (LDS). Here we describe a new class of ATG8 interactors that exploit ubiquitin-interacting motif (UIM)-like sequences for high-affinity binding to an alternative ATG8 interaction site. Assays with candidate UIM-containing proteins together with unbiased screens identified a large collection of UIM-based ATG8 interactors in plants, yeast, and humans. Analysis of a subset also harboring ubiquitin regulatory X (UBX) domains revealed a role for UIM-directed autophagy in clearing non-functional CDC48/p97 complexes, including some impaired in human disease. With this new class of adaptors and receptors, we greatly extend the reach of selective autophagy and identify new factors regulating autophagic vesicle dynamics.

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INTRODUCTION: Bone transport appears to be a solution for segmental bone defects; specifically, the "docking site" is where the transported segment meets the target segment at the end of the process. A lack of its consolidation is one of the major causes of failure for this technique. Many studies have been performed in order to enhance the consolidation of the docking site, but histological changes occurring in it remain unknown. The aim of this study was to determine microscopic changes present in this area, from distraction to remodeling, in order to clarify the best options to facilitate the success of this technique. MATERIALS AND METHODS: Ten adult sheep were submitted to bone transport using an Ilizarov external fixator. Histomorphometry and immunohistochemical studies were performed in the docking site to determine the main types of ossification, the evolutions of tissues and blood vessels and the distributions of collagen I and II. RESULTS: Ossification was mainly intramembranous with some areas of endochondral ossification. Fibrous tissue was predominant until 98 days after surgery. The area occupied by blood vessels increased until 50 days after surgery, when it decreased slowly until the end of the study. CONCLUSIONS: As far as the authors know, this is the first histological study performed in the docking site reporting the complete evolution of tissues until the end of remodeling, showing results contrary to those published by others authors. This could help to clarify information about its union and may be useful for future investigations about techniques for improving the consolidation of the docking site in humans.

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BACKGROUND: Mitogen-activated protein kinase (MAPK) cascades play critical functions in almost every aspect of plant growth and development, which regulates many physiological and biochemical processes. As a middle nodal point of the MAPK cascades, although evolutionary analysis of MKK from individual plant families had some reports, their evolutionary history in entire plants is still not clear. RESULTS: To better understand the evolution and function of plant MKKs, we performed systematical molecular evolutionary analysis of the MAPKK gene family and also surveyed their gene organizations, sequence features and expression patterns in different subfamilies. Phylogenetic analysis showed that plant MAPKK fall into five different groups (Group A-E). Majority orthology groups seemed to be a single or low-copy genes in all plant species analyzed in Group B, C and D, whereas group A MKKs undergo several duplication events, generating multiple gene copies. Further analysis showed that these duplication events were on account of whole genome duplications (WGDs) in plants and the duplicate genes maybe have undergone functional divergence. We also found that group E MKKs had mutation with one change of serine or theronine might lead to inactivity originated through the ancient tandem duplicates in monocots. Moreover, we also identified MKK3 integrated NTF2 domain that might have gradually lost the cytoplasmic-nuclear trafficking activity, which suggests that they may involve with the gene function more and more sophistication in the evolutionary process. Moreover, expression analyses indicated that plant MKK genes play probable roles in UV-B signaling. CONCLUSION: In general, ancient gene and genome duplications are significantly conducive to the expansion of the plant MKK gene family. Our study reveals two distinct evolutionary patterns for plant MKK proteins and sheds new light on the functional evolution of this gene family.

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