{"gene":"MELK","run_date":"2026-04-28T18:30:28","timeline":{"discoveries":[{"year":1997,"finding":"MELK encodes a protein with a kinase catalytic domain and a leucine zipper motif, identified as a new member of the Snf1/AMPK family of kinases, expressed in mouse eggs and preimplantation embryos.","method":"Differential display analysis of cDNA libraries, sequence analysis","journal":"Molecular reproduction and development","confidence":"Medium","confidence_rationale":"Tier 2 — original cloning and domain characterization, single lab","pmids":["9136115"],"is_preprint":false},{"year":2003,"finding":"MELK inhibits spliceosome assembly through interaction with the phosphothreonine-binding FHA domain of NIPP1; this interaction requires phosphorylation of Thr-478 of MELK and is increased in mitotically arrested cells. The splicing inhibition is independent of MELK kinase activity but requires the NIPP1-binding site (T478).","method":"Recombinant protein interaction assays, in vitro spliceosome assembly assays, kinase-dead mutant and T478A mutation analysis, cell fractionation from mitotic arrest","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution with mutagenesis validating mechanism","pmids":["14699119"],"is_preprint":false},{"year":2005,"finding":"MELK has broad substrate specificity with 16 autophosphorylation sites (including serines, threonines, and a tyrosine); phosphorylation of Thr167 and Ser171 is required for MELK activation. MELK activity also requires reducing agents and is inhibited by physiological Ca2+ concentrations. The N-terminal catalytic domain plus flanking ubiquitin-associated (UBA) domain is the minimal active fragment, and a C-terminal fragment functions as an autoinhibitory domain.","method":"In vitro kinase assay, mass spectrometry mapping of phosphorylation sites, site-directed mutagenesis, domain truncation analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro biochemical reconstitution with mutagenesis, multiple orthogonal methods","pmids":["16216881"],"is_preprint":false},{"year":2005,"finding":"MELK (Melk) is a direct transcriptional target of E2F; its expression is repressed by 1,25-dihydroxyvitamin D3 in a p107/p130-dependent (but not pRb-dependent) manner. Transfection studies and site-directed mutagenesis of E2F binding sites confirmed Melk as a bona fide E2F target gene.","method":"Transfection studies, site-directed mutagenesis of E2F binding sites, cDNA microarrays, p107/p130/pRb knockout cell analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — mutagenesis of regulatory sites plus genetic validation in knockout cells","pmids":["16144839"],"is_preprint":false},{"year":2005,"finding":"MELK is required for proliferation of multipotent neural progenitors (MNPs); overexpression enhances neurosphere formation while knockdown diminishes it. MELK expression is cell cycle-regulated in MNPs, and MELK knockdown downregulates B-myb expression, which also mediates MNP proliferation.","method":"Overexpression, siRNA knockdown, neurosphere formation assay, transgenic mice, in vitro culture","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal gain/loss-of-function with defined phenotype, replicated in multiple model systems","pmids":["16061694"],"is_preprint":false},{"year":2006,"finding":"The C. elegans MELK ortholog PIG-1 (a PAR-1/Kin1/SAD-1 family member) regulates cell size asymmetry in neuroblast divisions; pig-1 mutants produce daughters more equal in size with transformed apoptotic fate, indicating a role in cell polarity rather than solely cell cycle control.","method":"Genetic mutant analysis in C. elegans, lineage tracing","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — clean genetic loss-of-function with defined cellular phenotype in established model organism ortholog","pmids":["16774992"],"is_preprint":false},{"year":2006,"finding":"During M-phase, Xenopus MELK (xMELK) is phosphorylated at T414, T449, T451, T481, and S498; phosphorylations at T449, T451, T481 are mitosis-specific. MPF and MAPK directly phosphorylate xMELK (MPF phosphorylates T481), and these phosphorylations enhance xMELK kinase activity in vitro.","method":"M-phase egg extract phosphorylation mapping, in vitro kinase assays with MPF and MAPK, in vivo phosphorylation analysis","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 1 — direct in vitro kinase assay with site mapping and functional validation","pmids":["16628004"],"is_preprint":false},{"year":2007,"finding":"MELK physically interacts with and phosphorylates the long isoform of Bcl-G (Bcl-GL), a pro-apoptotic Bcl-2 family member, in vitro; overexpression of wild-type but not kinase-dead (D150A) MELK suppresses Bcl-GL-induced apoptosis, indicating MELK kinase activity is required for this anti-apoptotic function.","method":"Pull-down assay with recombinant wild-type and kinase-dead MELK, immunocomplex kinase assay, TUNEL assay, FACS analysis, siRNA knockdown","journal":"Breast cancer research : BCR","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay with kinase-dead mutant comparison plus cellular functional validation","pmids":["17280616"],"is_preprint":false},{"year":2011,"finding":"Xenopus MELK (xMELK) is required for cytokinesis completion; endogenous xMELK accumulates at the equatorial cortex of anaphase blastomeres and associates/colocalizes with the cytokinesis organizer anillin. Overexpression of xMELK impairs cytokinesis and abrogates accumulation of activated RhoA at the division furrow.","method":"Morpholino knockdown, live imaging, immunofluorescence, co-immunoprecipitation with anillin, RhoA localization assay in Xenopus embryo","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (knockdown, live imaging, co-IP, gain-of-function) in established MELK ortholog model","pmids":["21378312"],"is_preprint":false},{"year":2012,"finding":"C. elegans PAR-4 (LKB1) and its partners STRD-1 (STRAD) and MOP-25.2 (MO25) act in the same genetic pathway as PIG-1 (MELK ortholog) to promote asymmetric neuroblast divisions. A conserved threonine (T169) in the PIG-1 activation loop is essential for PIG-1 activity, consistent with PAR-4-mediated phosphorylation and activation of PIG-1. PIG-1 localizes to centrosomes during Q lineage divisions.","method":"Genetic epistasis analysis, site-directed mutagenesis (T169A), GFP localization, C. elegans genetics","journal":"Genetics","confidence":"High","confidence_rationale":"Tier 1-2 — genetic epistasis with mutagenesis of activation loop, conserved mechanism","pmids":["23267054"],"is_preprint":false},{"year":2013,"finding":"MELK forms a protein complex with FOXM1 in glioma stem cells, leading to MELK kinase-dependent phosphorylation and activation of FOXM1, which increases mitotic regulatory gene expression. PLK1 additionally trans-phosphorylates FOXM1 in this complex.","method":"Co-immunoprecipitation, kinase assay, siRNA knockdown, transgenic mouse NPCs, neurosphere formation","journal":"Stem cells (Dayton, Ohio)","confidence":"High","confidence_rationale":"Tier 2 — Co-IP plus functional kinase-dependent cellular phenotype, highly cited","pmids":["23404835"],"is_preprint":false},{"year":2013,"finding":"MELK loss in glioblastoma cells causes G1/S cell cycle arrest via increased p21 expression, which is mediated by consecutive activation of ATM, Chk2, and p53. The p53 activation results not from p53 stabilization but from loss of MDMX (an inhibitor of p53 transactivation). MELK depletion leads to accumulation of DNA double-strand breaks during replication (γH2AX foci), increased stalled replication forks, and reduced fork progression speed, indicating MELK reduces replication stress.","method":"siRNA knockdown, cell cycle analysis, γH2AX foci, DNA fiber assay for fork progression, Western blotting, rescue with siRNA-resistant MELK","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods with rescue experiment establishing mechanism","pmids":["23836907"],"is_preprint":false},{"year":2013,"finding":"MELK is regulated by the JNK signaling pathway and forms a complex with the oncoprotein c-JUN in glioma stem cells but not in normal progenitors. MELK silencing induces p53 expression and MELK/p53 are mutually exclusive; MELK silencing-mediated apoptosis is partially rescued by p53 inhibition or silencing, placing MELK action upstream of p53.","method":"shRNA knockdown, co-immunoprecipitation, p53 inhibitor pharmacological rescue, p53 siRNA rescue, intracranial tumor model","journal":"Stem cells (Dayton, Ohio)","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP, epistasis via pharmacological and genetic rescue, in vivo validation","pmids":["23339114"],"is_preprint":false},{"year":2013,"finding":"Crystal structure of MELK in complex with AMP-PNP and nanomolar inhibitors was determined, characterizing the kinase active site and the role of the UBA domain in inhibitor binding.","method":"X-ray crystallography, structure-based drug design analysis","journal":"Biochemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structure with functional domain characterization","pmids":["23914841"],"is_preprint":false},{"year":2013,"finding":"RACK1 (Receptor for Activated protein Kinase C) is an xMELK-interacting partner that co-localizes with xMELK at the tight junction in Xenopus embryo epithelial cells. A truncated RACK1 construct interferes with the localization of interphase MELK at cell-cell contacts, indicating RACK1 mediates MELK recruitment to the apical junctional complex.","method":"Co-immunoprecipitation, immunofluorescence, dominant-negative RACK1 construct, live cell imaging in Xenopus","journal":"Biology open","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP with localization data; single study","pmids":["24167714"],"is_preprint":false},{"year":2014,"finding":"MELK is identified as an oncogenic kinase in basal-like breast cancer (BBC) from a kinome-wide in vivo tumorigenesis screen; MELK overexpression in BBC is largely dependent on FoxM1 transcriptional regulation. Ablation of MELK selectively impairs proliferation in basal-like but not luminal breast cancer cells; MELK depletion induces caspase-dependent cell death preceded by defective mitosis.","method":"ORF kinome screen, shRNA knockdown, in vitro and xenograft proliferation assays, cell death assays, conditional Melk knockout mice","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — kinome screen plus multiple functional assays, highly cited","pmids":["24844244"],"is_preprint":false},{"year":2014,"finding":"Crystal structure of MPK38/MELK (T167E active mutant) in complex with the MELK-selective inhibitor OTSSP167 was determined, revealing detailed protein-inhibitor interactions at the active site.","method":"X-ray crystallography","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 — crystal structure of MELK-inhibitor complex","pmids":["24657156"],"is_preprint":false},{"year":2015,"finding":"EZH2 is targeted by the MELK-FOXM1 complex in glioma stem cells, promoting radiation resistance; the MELK-EZH2 axis is evolutionarily conserved in C. elegans. MELK or FOXM1 loss reduces EZH2 activity and sensitizes GSCs to radiation.","method":"Gain- and loss-of-function (shRNA, overexpression), C. elegans genetic analysis, correlation in clinical GBM samples","journal":"Stem cell reports","confidence":"High","confidence_rationale":"Tier 2 — multiple cell/organism models with defined mechanism, cross-species conservation","pmids":["25601206"],"is_preprint":false},{"year":2016,"finding":"MELK phosphorylates eIF4B at Ser406 during mitosis; this MELK-eIF4B signaling axis regulates protein synthesis specifically during mitosis, including synthesis of the anti-apoptotic protein MCL1. Inactivation of MELK or eIF4B reduces MCL1 protein synthesis and induces apoptotic cell death in cancer cells.","method":"Immunoprecipitation/mass spectrometry, peptide library profiling, in vitro kinase assay, protein synthesis measurement, Western blotting, siRNA knockdown","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — IP/MS substrate identification combined with in vitro kinase assay and functional cellular validation","pmids":["27528663"],"is_preprint":false},{"year":2016,"finding":"MELK inhibition (genetic and pharmacological) reduces DNA damage repair, sensitizing breast cancer cells to radiation; MELK knockdown was associated with impaired γH2AX clearance after radiation in vitro and delayed tumor growth after irradiation in vivo.","method":"shRNA knockdown, γH2AX staining, clonogenic survival assay, xenograft irradiation model","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — multiple methods but primarily phenomenological; single lab","pmids":["27225691"],"is_preprint":false},{"year":2017,"finding":"MELK is transcriptionally upregulated by MAPK pathway via transcription factor E2F1 in melanoma cells. MELK promotes melanoma growth by activating NF-κB pathway activity via Sequestosome 1 (SQSTM1/p62); SILAC phosphoproteomic analysis identified 469 proteins with reduced phosphorylation after MELK inhibition, including 139 BRAF/MEK substrates.","method":"SILAC phosphoproteomics, shRNA knockdown, pharmacological inhibition, NF-κB reporter assay, Western blotting","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1-2 — quantitative phosphoproteomics combined with mechanistic pathway validation","pmids":["29212029"],"is_preprint":false},{"year":2017,"finding":"MELK phosphorylates HIV-1 capsid at Ser-149 in the multimerized HIV-1 core, triggering uncoating to promote viral cDNA synthesis. A phosphorylation-mimetic substitution at Ser-149 causes premature capsid disassembly and earlier cDNA synthesis but failure to enter the nucleus.","method":"Genetic screen in human T-cells, MELK depletion, in vitro phosphorylation assay, capsid disassembly assay, HIV-1 replication assay, site-directed mutagenesis of capsid Ser-149","journal":"PLoS pathogens","confidence":"High","confidence_rationale":"Tier 1 — direct in vitro phosphorylation with mutagenesis validation and functional cellular consequence","pmids":["28683086"],"is_preprint":false},{"year":2017,"finding":"MELK inhibition induces p21 expression in a p53-independent manner; FOXO1 and FOXO3, known transcriptional regulators of p21, are phosphorylated by MELK and are involved in p21 induction after MELK inhibition.","method":"MELK inhibitor (OTS167), siRNA knockdown in p53-deficient cell lines, Western blotting, cell cycle analysis","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 3 — indirect evidence for FOXO phosphorylation by MELK; mechanism partially characterized","pmids":["28938528"],"is_preprint":false},{"year":2017,"finding":"MELK inhibition by selective inhibitor HTH-01-091, CRISPR/Cas9 knockout, and chemical-induced protein degradation does not significantly affect cellular growth in common culture conditions of basal-like breast cancer cells, revealing selectivity issues with OTSSP167 and potential off-target effects of MELK-targeting shRNAs.","method":"CRISPR/Cas9 knockout, novel selective inhibitor HTH-01-091, chemical protein degradation (dTAG), RNAi, CRISPR interference, proliferation assay","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal genetic and chemical perturbants, directly addresses mechanistic controversy","pmids":["28926338"],"is_preprint":false},{"year":2017,"finding":"MELK bound to and phosphorylated EZH2 in medulloblastoma stem-like cells; EZH2-mediated methylation of MELK was also induced, forming a reciprocal regulatory loop. MELK-induced EZH2 phosphorylation and EZH2-mediated MELK methylation together regulate proliferation of cancer stem-like cells.","method":"Co-immunoprecipitation, kinase assay, methylation assay, immunohistochemistry, xenograft","journal":"Molecular cancer research : MCR","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and kinase assay from single lab; reciprocal modification claim needs further validation","pmids":["28536141"],"is_preprint":false},{"year":2018,"finding":"MELK inhibition by the selective inhibitor NVS-MELK8a delays mitotic entry in cancer cells, associated with delayed activation of Aurora A, Aurora B, and CDK1. Live-cell microscopy confirmed 8a significantly lengthens G2 phase in a dose-dependent manner.","method":"MIB/MS selectivity profiling, resazurin/crystal violet growth assays, double-thymidine synchronization, Western blotting, live-cell microscopy with fluorescent PCNA","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — selective inhibitor with live-cell imaging validation; multiple orthogonal methods","pmids":["31896573"],"is_preprint":false},{"year":2018,"finding":"CRISPR/Cas9-generated MELK null mutant cancer cells of multiple types exhibit wild-type growth in vitro, under environmental stress, in the presence of cytotoxic chemotherapies, and in vivo; acute inhibition of MELK with a highly specific inhibitor also produces no specific anti-proliferative phenotype.","method":"CRISPR/Cas9 knockout in multiple cancer lines, specific MELK inhibitor, xenograft growth assay, chemotherapy combination","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 — rigorous genetic knockout across multiple cancer types with chemical validation","pmids":["29417930"],"is_preprint":false},{"year":2019,"finding":"MELK mediates EZH2 stability in extranodal NK/T-cell lymphoma through site-specific phosphorylation: MELK increases EZH2 S220 phosphorylation with concomitant loss of K222 ubiquitination, preventing proteasomal degradation of EZH2. USP36 was identified as the deubiquitinating enzyme that deubiquitinates EZH2 at K222. FOXM1 was not involved in this mechanism.","method":"Quantitative mass spectrometry, MELK chemical and genetic inhibition, ubiquitination assays, Western blotting, tissue microarray","journal":"Blood","confidence":"High","confidence_rationale":"Tier 1-2 — quantitative MS with site-specific phosphorylation and ubiquitination mapping plus functional validation","pmids":["31434700"],"is_preprint":false},{"year":2019,"finding":"MELK promotes ccRCC progression by phosphorylating PRAS40 (an inhibitory subunit of mTORC1), disrupting the interaction between PRAS40 and raptor, thereby over-activating mTORC1 signaling.","method":"Loss- and gain-of-function assays, co-immunoprecipitation, Western blotting, interaction disruption assay","journal":"Cell transplantation","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP-based mechanism; single lab, limited mutagenesis validation","pmids":["31813279"],"is_preprint":false},{"year":2019,"finding":"MPK38/MELK acts as an interacting partner and activator of p21; MPK38 phosphorylates p21 at Thr55, stimulating p21 nuclear translocation and association with PPARγ, preventing adipogenesis. MPK38 also stabilizes p21 by promoting CDK2-p21 and CDK4-p21 complex formation and reducing MDM2-p21 interaction.","method":"Co-immunoprecipitation, in vitro kinase assay, site-directed mutagenesis (T55A), nuclear fractionation, CRISPR knockin, adenoviral delivery in obese mice","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assay with site mutagenesis, CRISPR knockin validation, in vivo model","pmids":["31097688"],"is_preprint":false},{"year":2020,"finding":"CES-1 Snail (C. elegans) represses pig-1 MELK transcription in the NSM neuroblast lineage; PIG-1 MELK acts downstream of CES-1 to promote asymmetric neuroblast division by size and along the correct axis, establishing an auto-regulatory loop through which CES-1 Snail controls its own activity.","method":"Genome-wide CES-1 ChIP-seq, genetic epistasis, transcriptional reporter assays in C. elegans","journal":"Genetics","confidence":"High","confidence_rationale":"Tier 2 — genome-wide ChIP with genetic epistasis validation in established C. elegans model","pmids":["28652378"],"is_preprint":false},{"year":2020,"finding":"PIG-1 MELK (C. elegans ortholog) promotes apoptosis by phosphorylating nonmuscle myosin II, leading to cortical enrichment of myosin II prior to neuroblast division. This promotes partitioning of CES-1 Snail (an anti-apoptotic factor) away from the apoptotic daughter cell. pig-1 MELK is controlled by both a ces-1 Snail- and par-4 LKB1-dependent pathway.","method":"Genetic analysis in C. elegans, phosphorylation assay, live imaging, epistasis analysis","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis combined with biochemical phosphorylation assay, cross-validated with previous pig-1 studies","pmids":["32946434"],"is_preprint":false},{"year":2020,"finding":"MELK directly interacts with MLST8 (a component of mTOR complexes) and activates mTORC1 and mTORC2 signaling pathways in endometrial carcinoma. E2F1 transcriptionally regulates MELK expression, establishing an E2F1/MELK/mTORC1/2 axis.","method":"Co-immunoprecipitation, chromatin immunoprecipitation, luciferase reporter assay, Western blotting, xenograft model","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 3 — Co-IP for MELK-MLST8 interaction; single lab, mechanistic follow-up limited","pmids":["31915116"],"is_preprint":false},{"year":2020,"finding":"MELK inhibition arrests LUAD cells at G2/M phase via the PLK1-CDC25C-CDK1 pathway and triggers apoptosis-mediated pyroptosis. MELK knockdown inhibits migration/invasion potentially through Twist1, Slug, MMP7, and N-catenin.","method":"MELK inhibitor OTSSP167, shRNA knockdown, cell cycle analysis, apoptosis assay, Western blotting, invasion assay","journal":"Signal transduction and targeted therapy","confidence":"Medium","confidence_rationale":"Tier 3 — pathway placement by Western blot; mechanism not directly validated by mutagenesis","pmids":["33262323"],"is_preprint":false},{"year":2017,"finding":"Smad2, Smad3, and Smad4 increase MPK38/MELK-mediated ASK1/TGF-β/p53 signaling and stabilize MPK38 by attenuating its interaction with the negative regulator thioredoxin (Trx) and enhancing interaction with the positive regulator ZPR9. Smad7 has opposite effects. MPK38 phosphorylates Smads (Smad2 S245, Smad3 S204, Smad4 S343, Smad7 T96), and these phosphorylations are required for Smad effects on MPK38 activity.","method":"Co-immunoprecipitation, in vitro kinase assay, phosphorylation-defective mutants, adenoviral delivery in HFD-fed obese mice","journal":"Cell death & disease","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assay with mutagenesis, in vivo validation in obese mice","pmids":["29700281"],"is_preprint":false},{"year":2017,"finding":"ZPR9 is an activator of MPK38/MELK; the MPK38-ZPR9 association is mediated by cysteine residues (Cys269/Cys286 of MPK38; Cys305/Cys308 of ZPR9). MPK38 phosphorylates ZPR9 at Thr252, and wild-type (but not T252A mutant) ZPR9 enhances ASK1, TGF-β, and p53 function by stabilizing MPK38.","method":"Co-immunoprecipitation, in vitro kinase assay, CRISPR/Cas9 knockin (ZPR9 T252A), NIH 3T3 inducible knockdown, MPK38 kinase assay","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1-2 — in vitro kinase assay with mutagenesis and CRISPR knockin validation","pmids":["28195154"],"is_preprint":false},{"year":2023,"finding":"MELK activates the PI3K/mTOR signaling pathway and subsequently promotes DLAT (dihydrolipoamide S-acetyltransferase) expression, stabilizing mitochondrial function and respiration in HCC. This reduces intracellular ROS and decreases sensitivity to the copper ionophore elesclomol (cuproptosis), promoting HCC progression.","method":"MELK knockdown/overexpression, Western blotting, mitochondrial function assays, ROS measurement, copper ionophore treatment, xenograft","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 3 — pathway analysis by Western blot; mechanistic link between MELK and DLAT not directly established by kinase assay","pmids":["37949877"],"is_preprint":false},{"year":2024,"finding":"MELK binds to STAT3 and induces STAT3 phosphorylation in HCC, increasing expression of CCL2. This MELK-STAT3-CCL2 axis promotes M2 macrophage polarization and inhibits CD8+ T cell recruitment, contributing to an immunosuppressive tumor microenvironment.","method":"IP-MS, co-immunoprecipitation, luciferase assay, RNA sequencing, xenograft models, flow cytometry","journal":"Molecular cancer","confidence":"Medium","confidence_rationale":"Tier 2-3 — IP-MS identification with Co-IP validation and functional cellular assays; single lab","pmids":["38970074"],"is_preprint":false},{"year":2025,"finding":"MELK binds to FABP5 and affects its ubiquitination through the K48R pathway to increase FABP5 stability, thereby activating the AKT/mTOR signaling axis and weakening RFA-mediated antitumor immune effects in HCC.","method":"RNA sequencing, co-immunoprecipitation, ubiquitination assay, nanoparticle-mediated MELK inhibition, in vivo tumor models","journal":"Military Medical Research","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP with ubiquitination assay; mechanism partially characterized, single lab","pmids":["39871325"],"is_preprint":false},{"year":2020,"finding":"Wild-type p53 suppresses MELK expression by inhibiting E2F1-dependent transcription of FOXM1 (which in turn drives MELK expression). Mutation/loss of p53 de-represses FOXM1-driven MELK expression. ChIP assays showed wild-type p53 reduces E2F1 binding to the FOXM1 promoter.","method":"Promoter deletion studies, ChIP assay, overexpression of wild-type p53 in p53-null cells, Western blotting, gene expression analysis","journal":"NPJ breast cancer","confidence":"High","confidence_rationale":"Tier 2 — ChIP assay combined with promoter deletion and genetic rescue experiments","pmids":["31909186"],"is_preprint":false},{"year":2012,"finding":"MELK identified PSMA1 (proteasome subunit alpha type 1) and DBNL (drebrin-like) as novel substrates; MELK phosphorylates these substrates in vitro, and these substrates are important for stem-cell characteristics and invasiveness. OTSSP167 inhibits this phosphorylation.","method":"High-throughput screening, in vitro kinase assay with recombinant substrates, structure-activity relationship studies","journal":"Oncotarget","confidence":"Medium","confidence_rationale":"Tier 2-3 — substrate identification with kinase assay; functional consequences established indirectly","pmids":["23283305"],"is_preprint":false},{"year":2016,"finding":"MELK enhances DEPDC1 phosphorylation and its stability as a downstream molecule in the MELK signaling pathway; MELK inhibition by OTS167 reduces DEPDC1 expression in treated xenograft tumor tissues.","method":"Western blotting, in vitro kinase assay (implied), xenograft pharmacodynamic analysis","journal":"Oncotarget","confidence":"Low","confidence_rationale":"Tier 3 — pharmacological evidence only; direct kinase assay on DEPDC1 not fully described in abstract","pmids":["26918358"],"is_preprint":false},{"year":2018,"finding":"MELK inhibition in DIPG reduces inhibitory phosphorylation of PPARγ, resulting in increased nuclear translocation and consequent transcriptional activity of PPARγ, identifying a MELK-PPARγ signaling axis.","method":"RNA sequencing of MELK inhibitor-treated cells, Western blotting for PPARγ phosphorylation and localization, patient-derived DIPG cultures","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2-3 — RNA-seq-guided mechanism with Western blot validation; direct kinase assay on PPARγ not demonstrated","pmids":["30061363"],"is_preprint":false},{"year":2024,"finding":"DDX56 enhances MELK expression in HCC, and MELK in turn promotes FOXM1 expression/activity; DDX56 knockdown reduces MELK-mediated FOXM1 signaling, establishing a DDX56-MELK-FOXM1 axis regulating cancer stemness and EMT in HCC.","method":"shRNA knockdown, Western blotting, xenograft model with lung metastasis assessment","journal":"iScience","confidence":"Low","confidence_rationale":"Tier 3 — pathway placement by knockdown and Western blot without direct biochemical validation of mechanism","pmids":["38827395"],"is_preprint":false}],"current_model":"MELK is a conserved Snf1/AMPK-family serine/threonine kinase whose activity is cell-cycle regulated, peaking during mitosis, where it is activated by autophosphorylation at Thr167/Ser171 and by MPF/MAPK-mediated phosphorylation; MELK promotes cell proliferation and mitotic progression through multiple substrates and effectors, including FOXM1 (direct phosphorylation and activation), eIF4B (Ser406 phosphorylation to sustain MCL1 synthesis during mitosis), EZH2 (phosphorylation at S220 to prevent ubiquitin-mediated degradation), Bcl-GL (phosphorylation to suppress pro-apoptotic activity), p21 (Thr55 phosphorylation), and PRAS40 (phosphorylation to activate mTORC1); MELK also controls spliceosome assembly through phosphorylation-dependent interaction with NIPP1, reduces replication stress in cancer cells (linked to MDMX-p53 regulation), promotes cytokinesis via association with anillin and regulation of RhoA at the division furrow, and in its C. elegans ortholog PIG-1 form, promotes apoptotic fate specification by phosphorylating nonmuscle myosin II to partition CES-1 Snail asymmetrically—while CRISPR-based studies have challenged its essentiality for basal proliferation, indicating context-dependent roles."},"narrative":{"teleology":[{"year":1997,"claim":"Identification of MELK as a novel Snf1/AMPK-family kinase with a leucine zipper motif established a new kinase gene expressed in early embryonic development, opening the question of its substrate specificity and biological function.","evidence":"Differential display cloning from mouse egg/preimplantation embryo cDNA libraries with sequence analysis","pmids":["9136115"],"confidence":"Medium","gaps":["No substrates or cellular function identified","Expression pattern limited to mouse early embryo"]},{"year":2005,"claim":"Biochemical dissection revealed that MELK activation requires autophosphorylation at Thr167/Ser171, that a UBA domain is part of the minimal active fragment, and that a C-terminal domain is autoinhibitory — establishing the enzymological framework for understanding MELK regulation.","evidence":"In vitro kinase assay, mass spectrometry phosphorylation mapping, site-directed mutagenesis, domain truncation analysis","pmids":["16216881"],"confidence":"High","gaps":["Upstream activating kinase not yet identified in mammalian cells","Structural basis of autoinhibition unresolved"]},{"year":2003,"claim":"Discovery that MELK inhibits spliceosome assembly through phosphorylation-dependent interaction with NIPP1's FHA domain revealed a non-canonical role for MELK in RNA processing, linking MELK to mitotic translational regulation.","evidence":"Recombinant protein interaction assays, in vitro spliceosome reconstitution, T478A mutagenesis, mitotic cell fractionation","pmids":["14699119"],"confidence":"High","gaps":["Physiological relevance of splicing inhibition during mitosis not demonstrated in vivo","Whether MELK kinase activity targets other spliceosome components unknown"]},{"year":2005,"claim":"Identification of MELK as an E2F transcriptional target and its requirement for neural progenitor proliferation established MELK as a cell-cycle-coupled proliferative kinase in stem/progenitor cells, with B-myb as a downstream mediator.","evidence":"E2F site mutagenesis in Melk promoter, p107/p130 knockout cell analysis, siRNA knockdown and overexpression in neurosphere assays","pmids":["16144839","16061694"],"confidence":"High","gaps":["Direct phosphorylation targets mediating progenitor proliferation not identified","Relationship between MELK and B-myb not biochemically defined"]},{"year":2006,"claim":"Mapping of mitosis-specific phosphorylation sites on Xenopus MELK by MPF and MAPK, and identification of PIG-1 (C. elegans ortholog) as a regulator of asymmetric cell division, expanded MELK's role beyond proliferation to mitotic regulation and cell fate determination.","evidence":"Xenopus M-phase extract phosphorylation mapping with in vitro kinase assays; C. elegans pig-1 mutant lineage tracing","pmids":["16628004","16774992"],"confidence":"High","gaps":["Mammalian equivalents of MPF/MAPK-mediated activation sites not confirmed","How PIG-1 mechanistically controls cell size asymmetry unknown"]},{"year":2007,"claim":"Demonstration that MELK phosphorylates the pro-apoptotic Bcl-GL protein and that kinase activity is required to suppress Bcl-GL-induced apoptosis established MELK as a direct anti-apoptotic kinase.","evidence":"Recombinant pull-down, immunocomplex kinase assay with kinase-dead D150A mutant, TUNEL/FACS apoptosis assays","pmids":["17280616"],"confidence":"High","gaps":["Bcl-GL phosphorylation site not mapped","In vivo relevance of MELK-Bcl-GL axis not tested"]},{"year":2011,"claim":"Localization of Xenopus MELK to the cleavage furrow and its interaction with anillin, combined with overexpression-induced loss of RhoA accumulation, established a direct role for MELK in cytokinesis.","evidence":"Morpholino knockdown, live imaging, co-immunoprecipitation with anillin, RhoA localization in Xenopus embryo","pmids":["21378312"],"confidence":"High","gaps":["Whether MELK directly phosphorylates anillin or RhoA regulators unknown","Mammalian cytokinesis role not confirmed"]},{"year":2012,"claim":"Genetic epistasis in C. elegans placed PIG-1/MELK downstream of PAR-4/LKB1 in asymmetric neuroblast division, with activation loop T169 phosphorylation essential, establishing a conserved LKB1-MELK kinase cascade controlling cell polarity.","evidence":"Genetic epistasis with par-4/strd-1/mop-25.2, T169A mutagenesis, GFP localization in C. elegans","pmids":["23267054"],"confidence":"High","gaps":["Direct phosphorylation of PIG-1 by PAR-4 not biochemically demonstrated","Whether mammalian LKB1 activates MELK in vivo not shown"]},{"year":2013,"claim":"Multiple studies converged to identify FOXM1 as a direct MELK substrate in glioma stem cells, established that MELK loss causes replication stress and p53-dependent cell cycle arrest, and resolved the MELK crystal structure — collectively defining MELK as a mitotic kinase hub linking DNA integrity, transcription, and structural drug design.","evidence":"Co-IP/kinase assay for FOXM1; DNA fiber assay and γH2AX for replication stress; X-ray crystallography of MELK-AMP-PNP and inhibitor complexes","pmids":["23404835","23836907","23914841","23339114"],"confidence":"High","gaps":["FOXM1 phosphorylation sites by MELK not mapped","How MELK prevents replication stress mechanistically unclear","Whether MELK-JUN complex is direct or scaffolded unknown"]},{"year":2014,"claim":"A kinome-wide screen identified MELK as an oncogenic kinase selectively required in basal-like breast cancer (BBC), with FOXM1 driving its transcription, suggesting a FOXM1-MELK positive feedback loop in aggressive breast cancer subtypes.","evidence":"ORF kinome screen, shRNA knockdown, xenograft proliferation, conditional Melk knockout mice","pmids":["24844244"],"confidence":"High","gaps":["Mechanism of basal-like selectivity not defined","Direct evidence for positive feedback loop incomplete"]},{"year":2016,"claim":"Identification of eIF4B Ser406 as a direct mitotic MELK substrate controlling MCL1 protein synthesis revealed how MELK sustains anti-apoptotic protein levels specifically during mitosis, linking MELK to translational control.","evidence":"IP/MS substrate identification, peptide library profiling, in vitro kinase assay, protein synthesis measurement","pmids":["27528663"],"confidence":"High","gaps":["Whether other mRNAs are translationally regulated by MELK-eIF4B unknown","In vivo validation of eIF4B-MCL1 axis not performed"]},{"year":2017,"claim":"CRISPR knockout, chemical degradation, and highly selective inhibitors revealed that MELK is dispensable for basal proliferation of breast cancer cells under standard conditions, challenging prior RNAi-based essentiality claims and demonstrating off-target effects of OTSSP167.","evidence":"CRISPR/Cas9 knockout, selective inhibitor HTH-01-091, dTAG chemical degradation, proliferation assays in multiple BBC lines","pmids":["28926338"],"confidence":"High","gaps":["Context-specific conditions under which MELK becomes essential not systematically defined","Whether MELK is essential in vivo under stress or immune challenge not addressed"]},{"year":2017,"claim":"Phosphoproteomic analysis in melanoma linked MELK to MAPK/E2F1 transcriptional control and NF-κB activation via SQSTM1/p62, while studies of Smad phosphorylation and ZPR9 activation expanded MELK's signaling network to TGF-β and ASK1 pathways.","evidence":"SILAC phosphoproteomics; Co-IP and in vitro kinase assays with Smad and ZPR9 phosphorylation-defective mutants; CRISPR knockin of ZPR9 T252A","pmids":["29212029","29700281","28195154"],"confidence":"High","gaps":["How MELK activates NF-κB via p62 mechanistically unresolved","Smad-MELK axis validated primarily in adipogenesis context"]},{"year":2018,"claim":"Confirmation that CRISPR-null MELK cancer cells grow normally across multiple cancer types and conditions, combined with evidence that selective MELK inhibition delays mitotic entry via delayed Aurora A/B and CDK1 activation, refined the view that MELK is not a general cancer dependency but does regulate G2/M timing.","evidence":"CRISPR knockout in multiple cancer lines with xenograft; selective inhibitor NVS-MELK8a with live-cell PCNA imaging and synchronization","pmids":["29417930","31896573"],"confidence":"High","gaps":["Mechanism by which MELK regulates Aurora/CDK1 activation not biochemically defined","Whether genetic compensation masks MELK loss in knockouts not tested"]},{"year":2019,"claim":"Direct phosphorylation of EZH2 at S220 by MELK was shown to prevent K222 ubiquitination and proteasomal degradation (with USP36 as the deubiquitinase), establishing a site-specific mechanism for MELK-dependent EZH2 stabilization distinct from FOXM1-mediated effects.","evidence":"Quantitative mass spectrometry, ubiquitination assays, MELK chemical and genetic inhibition in NK/T-cell lymphoma","pmids":["31434700"],"confidence":"High","gaps":["Whether MELK directly phosphorylates EZH2 or acts through an intermediate kinase not fully excluded","Generalizability beyond NK/T-cell lymphoma not established"]},{"year":2019,"claim":"MELK was shown to phosphorylate p21 at Thr55, promoting nuclear translocation, CDK complex formation, and association with PPARγ to inhibit adipogenesis, revealing a metabolic regulatory function for MELK beyond cancer.","evidence":"In vitro kinase assay, T55A mutagenesis, CRISPR knockin, adenoviral delivery in obese mice","pmids":["31097688"],"confidence":"High","gaps":["Whether Thr55 phosphorylation of p21 by MELK occurs in cancer contexts not shown","Relative contribution of MELK vs. other Thr55 kinases in vivo unknown"]},{"year":2020,"claim":"C. elegans studies established that PIG-1/MELK promotes apoptotic fate by phosphorylating nonmuscle myosin II to partition CES-1 Snail asymmetrically, within an autoregulatory circuit where CES-1 represses pig-1 transcription, providing a complete mechanistic model for MELK-driven asymmetric cell fate.","evidence":"ChIP-seq for CES-1, genetic epistasis, phosphorylation assay, live imaging in C. elegans","pmids":["28652378","32946434"],"confidence":"High","gaps":["Whether mammalian MELK phosphorylates myosin II or controls asymmetric division similarly is unknown","Structural basis of PIG-1-myosin II interaction not determined"]},{"year":2024,"claim":"MELK was linked to tumor immune evasion through STAT3 phosphorylation driving CCL2 expression and M2 macrophage polarization, and to FABP5 stabilization activating AKT/mTOR, expanding MELK's roles to immunomodulation in hepatocellular carcinoma.","evidence":"IP-MS and Co-IP for STAT3; Co-IP and ubiquitination assay for FABP5; xenograft models with immune profiling","pmids":["38970074","39871325"],"confidence":"Medium","gaps":["Whether MELK directly phosphorylates STAT3 or FABP5 not shown by in vitro kinase assay","Immunomodulatory role not validated in immunocompetent genetic models","Single-lab findings for each axis"]},{"year":null,"claim":"It remains unresolved under which physiological or pathological conditions MELK becomes essential, given that CRISPR knockouts show no proliferative defect; whether genetic compensation or context-dependent stress unmasks MELK dependence is a central open question.","evidence":"","pmids":[],"confidence":"High","gaps":["Conditions conferring MELK essentiality not systematically identified","No comprehensive interactome under stress conditions","In vivo immune-competent models of MELK loss largely absent"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[2,7,10,18,21,27,29,34,35]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[2,6,7,18,21,27,29,34]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,28,32]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,18]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[8,14]},{"term_id":"GO:0005815","term_label":"microtubule organizing center","supporting_discovery_ids":[9]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[29]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[4,6,8,15,18,25]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[7,18,31]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[20,28,32,34,37]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[3,10,39]},{"term_id":"R-HSA-8953854","term_label":"Metabolism of RNA","supporting_discovery_ids":[1]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[18,27]}],"complexes":["MELK-FOXM1 complex","MELK-NIPP1 complex"],"partners":["FOXM1","EZH2","NIPP1","ANLN","EIF4B","ZPR9","STAT3","MLST8"],"other_free_text":[]},"mechanistic_narrative":"MELK is a cell-cycle-regulated Snf1/AMPK-family serine/threonine kinase that promotes mitotic progression, cell proliferation, and survival through phosphorylation of diverse substrates. Activated by autophosphorylation at Thr167/Ser171 and by mitotic kinases MPF and MAPK, MELK phosphorylates FOXM1 to drive mitotic gene expression, eIF4B at Ser406 to sustain MCL1 translation during mitosis, EZH2 at S220 to prevent its ubiquitin-mediated degradation, Bcl-GL to suppress apoptosis, p21 at Thr55 to regulate nuclear translocation, and Smad proteins to modulate TGF-β/p53 signaling [PMID:16216881, PMID:23404835, PMID:27528663, PMID:31434700, PMID:17280616, PMID:31097688, PMID:29700281]. MELK also inhibits spliceosome assembly through phosphorylation-dependent binding to NIPP1, participates in cytokinesis via association with anillin and regulation of RhoA at the cleavage furrow, and reduces replication stress in cancer cells [PMID:14699119, PMID:21378312, PMID:23836907]. CRISPR knockout studies across multiple cancer cell lines reveal that MELK is dispensable for basal proliferation under standard conditions, indicating context-dependent essentiality despite its prominent expression in aggressive cancers [PMID:28926338, PMID:29417930]."},"prefetch_data":{"uniprot":{"accession":"Q14680","full_name":"Maternal embryonic leucine zipper kinase","aliases":["Protein kinase Eg3","pEg3 kinase","Protein kinase PK38","hPK38","Tyrosine-protein kinase MELK"],"length_aa":651,"mass_kda":74.6,"function":"Serine/threonine-protein kinase involved in various processes such as cell cycle regulation, self-renewal of stem cells, apoptosis and splicing regulation. Has a broad substrate specificity; phosphorylates BCL2L14, CDC25B, MAP3K5/ASK1 and ZNF622. Acts as an activator of apoptosis by phosphorylating and activating MAP3K5/ASK1. Acts as a regulator of cell cycle, notably by mediating phosphorylation of CDC25B, promoting localization of CDC25B to the centrosome and the spindle poles during mitosis. Plays a key role in cell proliferation and carcinogenesis. Required for proliferation of embryonic and postnatal multipotent neural progenitors. Phosphorylates and inhibits BCL2L14, possibly leading to affect mammary carcinogenesis by mediating inhibition of the pro-apoptotic function of BCL2L14. Also involved in the inhibition of spliceosome assembly during mitosis by phosphorylating ZNF622, thereby contributing to its redirection to the nucleus. May also play a role in primitive hematopoiesis","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q14680/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MELK","classification":"Not Classified","n_dependent_lines":10,"n_total_lines":1208,"dependency_fraction":0.008278145695364239},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000165304","cell_line_id":"CID001220","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"nucleoplasm","grade":1},{"compartment":"vesicles","grade":1}],"interactors":[{"gene":"FKBP5","stoichiometry":0.2},{"gene":"PSMG2","stoichiometry":0.2},{"gene":"PSMG4","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001220","total_profiled":1310},"omim":[{"mim_id":"608694","title":"ZINC FINGER PROTEIN 622; ZNF622","url":"https://www.omim.org/entry/608694"},{"mim_id":"608130","title":"NUAK FAMILY, SNF1-LIKE KINASE, 1; NUAK1","url":"https://www.omim.org/entry/608130"},{"mim_id":"607025","title":"MATERNAL EMBRYONIC LEUCINE ZIPPER KINASE; MELK","url":"https://www.omim.org/entry/607025"},{"mim_id":"600540","title":"TRANSCRIPTION FACTOR Sp4; SP4","url":"https://www.omim.org/entry/600540"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"bone marrow","ntpm":9.6},{"tissue":"lymphoid tissue","ntpm":19.6}],"url":"https://www.proteinatlas.org/search/MELK"},"hgnc":{"alias_symbol":["KIAA0175"],"prev_symbol":[]},"alphafold":{"accession":"Q14680","domains":[{"cath_id":"1.10.510.10","chopping":"3-89_294-327","consensus_level":"high","plddt":93.1398,"start":3,"end":327},{"cath_id":"1.10.510.10","chopping":"93-265","consensus_level":"high","plddt":90.0289,"start":93,"end":265},{"cath_id":"3.30.310.80","chopping":"556-649","consensus_level":"high","plddt":86.0788,"start":556,"end":649}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14680","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q14680-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q14680-F1-predicted_aligned_error_v6.png","plddt_mean":69.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MELK","jax_strain_url":"https://www.jax.org/strain/search?query=MELK"},"sequence":{"accession":"Q14680","fasta_url":"https://rest.uniprot.org/uniprotkb/Q14680.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q14680/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q14680"}},"corpus_meta":[{"pmid":"23404835","id":"PMC_23404835","title":"MELK-dependent 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\"confidence_rationale\": \"Tier 2 — original cloning and domain characterization, single lab\",\n      \"pmids\": [\"9136115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MELK inhibits spliceosome assembly through interaction with the phosphothreonine-binding FHA domain of NIPP1; this interaction requires phosphorylation of Thr-478 of MELK and is increased in mitotically arrested cells. The splicing inhibition is independent of MELK kinase activity but requires the NIPP1-binding site (T478).\",\n      \"method\": \"Recombinant protein interaction assays, in vitro spliceosome assembly assays, kinase-dead mutant and T478A mutation analysis, cell fractionation from mitotic arrest\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution with mutagenesis validating mechanism\",\n      \"pmids\": [\"14699119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MELK has broad substrate specificity with 16 autophosphorylation sites (including serines, threonines, and a tyrosine); phosphorylation of Thr167 and Ser171 is required for MELK activation. MELK activity also requires reducing agents and is inhibited by physiological Ca2+ concentrations. The N-terminal catalytic domain plus flanking ubiquitin-associated (UBA) domain is the minimal active fragment, and a C-terminal fragment functions as an autoinhibitory domain.\",\n      \"method\": \"In vitro kinase assay, mass spectrometry mapping of phosphorylation sites, site-directed mutagenesis, domain truncation analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro biochemical reconstitution with mutagenesis, multiple orthogonal methods\",\n      \"pmids\": [\"16216881\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MELK (Melk) is a direct transcriptional target of E2F; its expression is repressed by 1,25-dihydroxyvitamin D3 in a p107/p130-dependent (but not pRb-dependent) manner. Transfection studies and site-directed mutagenesis of E2F binding sites confirmed Melk as a bona fide E2F target gene.\",\n      \"method\": \"Transfection studies, site-directed mutagenesis of E2F binding sites, cDNA microarrays, p107/p130/pRb knockout cell analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mutagenesis of regulatory sites plus genetic validation in knockout cells\",\n      \"pmids\": [\"16144839\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MELK is required for proliferation of multipotent neural progenitors (MNPs); overexpression enhances neurosphere formation while knockdown diminishes it. MELK expression is cell cycle-regulated in MNPs, and MELK knockdown downregulates B-myb expression, which also mediates MNP proliferation.\",\n      \"method\": \"Overexpression, siRNA knockdown, neurosphere formation assay, transgenic mice, in vitro culture\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal gain/loss-of-function with defined phenotype, replicated in multiple model systems\",\n      \"pmids\": [\"16061694\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The C. elegans MELK ortholog PIG-1 (a PAR-1/Kin1/SAD-1 family member) regulates cell size asymmetry in neuroblast divisions; pig-1 mutants produce daughters more equal in size with transformed apoptotic fate, indicating a role in cell polarity rather than solely cell cycle control.\",\n      \"method\": \"Genetic mutant analysis in C. elegans, lineage tracing\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean genetic loss-of-function with defined cellular phenotype in established model organism ortholog\",\n      \"pmids\": [\"16774992\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"During M-phase, Xenopus MELK (xMELK) is phosphorylated at T414, T449, T451, T481, and S498; phosphorylations at T449, T451, T481 are mitosis-specific. MPF and MAPK directly phosphorylate xMELK (MPF phosphorylates T481), and these phosphorylations enhance xMELK kinase activity in vitro.\",\n      \"method\": \"M-phase egg extract phosphorylation mapping, in vitro kinase assays with MPF and MAPK, in vivo phosphorylation analysis\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct in vitro kinase assay with site mapping and functional validation\",\n      \"pmids\": [\"16628004\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MELK physically interacts with and phosphorylates the long isoform of Bcl-G (Bcl-GL), a pro-apoptotic Bcl-2 family member, in vitro; overexpression of wild-type but not kinase-dead (D150A) MELK suppresses Bcl-GL-induced apoptosis, indicating MELK kinase activity is required for this anti-apoptotic function.\",\n      \"method\": \"Pull-down assay with recombinant wild-type and kinase-dead MELK, immunocomplex kinase assay, TUNEL assay, FACS analysis, siRNA knockdown\",\n      \"journal\": \"Breast cancer research : BCR\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay with kinase-dead mutant comparison plus cellular functional validation\",\n      \"pmids\": [\"17280616\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Xenopus MELK (xMELK) is required for cytokinesis completion; endogenous xMELK accumulates at the equatorial cortex of anaphase blastomeres and associates/colocalizes with the cytokinesis organizer anillin. Overexpression of xMELK impairs cytokinesis and abrogates accumulation of activated RhoA at the division furrow.\",\n      \"method\": \"Morpholino knockdown, live imaging, immunofluorescence, co-immunoprecipitation with anillin, RhoA localization assay in Xenopus embryo\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (knockdown, live imaging, co-IP, gain-of-function) in established MELK ortholog model\",\n      \"pmids\": [\"21378312\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"C. elegans PAR-4 (LKB1) and its partners STRD-1 (STRAD) and MOP-25.2 (MO25) act in the same genetic pathway as PIG-1 (MELK ortholog) to promote asymmetric neuroblast divisions. A conserved threonine (T169) in the PIG-1 activation loop is essential for PIG-1 activity, consistent with PAR-4-mediated phosphorylation and activation of PIG-1. PIG-1 localizes to centrosomes during Q lineage divisions.\",\n      \"method\": \"Genetic epistasis analysis, site-directed mutagenesis (T169A), GFP localization, C. elegans genetics\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — genetic epistasis with mutagenesis of activation loop, conserved mechanism\",\n      \"pmids\": [\"23267054\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MELK forms a protein complex with FOXM1 in glioma stem cells, leading to MELK kinase-dependent phosphorylation and activation of FOXM1, which increases mitotic regulatory gene expression. PLK1 additionally trans-phosphorylates FOXM1 in this complex.\",\n      \"method\": \"Co-immunoprecipitation, kinase assay, siRNA knockdown, transgenic mouse NPCs, neurosphere formation\",\n      \"journal\": \"Stem cells (Dayton, Ohio)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus functional kinase-dependent cellular phenotype, highly cited\",\n      \"pmids\": [\"23404835\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MELK loss in glioblastoma cells causes G1/S cell cycle arrest via increased p21 expression, which is mediated by consecutive activation of ATM, Chk2, and p53. The p53 activation results not from p53 stabilization but from loss of MDMX (an inhibitor of p53 transactivation). MELK depletion leads to accumulation of DNA double-strand breaks during replication (γH2AX foci), increased stalled replication forks, and reduced fork progression speed, indicating MELK reduces replication stress.\",\n      \"method\": \"siRNA knockdown, cell cycle analysis, γH2AX foci, DNA fiber assay for fork progression, Western blotting, rescue with siRNA-resistant MELK\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods with rescue experiment establishing mechanism\",\n      \"pmids\": [\"23836907\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MELK is regulated by the JNK signaling pathway and forms a complex with the oncoprotein c-JUN in glioma stem cells but not in normal progenitors. MELK silencing induces p53 expression and MELK/p53 are mutually exclusive; MELK silencing-mediated apoptosis is partially rescued by p53 inhibition or silencing, placing MELK action upstream of p53.\",\n      \"method\": \"shRNA knockdown, co-immunoprecipitation, p53 inhibitor pharmacological rescue, p53 siRNA rescue, intracranial tumor model\",\n      \"journal\": \"Stem cells (Dayton, Ohio)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP, epistasis via pharmacological and genetic rescue, in vivo validation\",\n      \"pmids\": [\"23339114\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Crystal structure of MELK in complex with AMP-PNP and nanomolar inhibitors was determined, characterizing the kinase active site and the role of the UBA domain in inhibitor binding.\",\n      \"method\": \"X-ray crystallography, structure-based drug design analysis\",\n      \"journal\": \"Biochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure with functional domain characterization\",\n      \"pmids\": [\"23914841\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"RACK1 (Receptor for Activated protein Kinase C) is an xMELK-interacting partner that co-localizes with xMELK at the tight junction in Xenopus embryo epithelial cells. A truncated RACK1 construct interferes with the localization of interphase MELK at cell-cell contacts, indicating RACK1 mediates MELK recruitment to the apical junctional complex.\",\n      \"method\": \"Co-immunoprecipitation, immunofluorescence, dominant-negative RACK1 construct, live cell imaging in Xenopus\",\n      \"journal\": \"Biology open\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP with localization data; single study\",\n      \"pmids\": [\"24167714\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"MELK is identified as an oncogenic kinase in basal-like breast cancer (BBC) from a kinome-wide in vivo tumorigenesis screen; MELK overexpression in BBC is largely dependent on FoxM1 transcriptional regulation. Ablation of MELK selectively impairs proliferation in basal-like but not luminal breast cancer cells; MELK depletion induces caspase-dependent cell death preceded by defective mitosis.\",\n      \"method\": \"ORF kinome screen, shRNA knockdown, in vitro and xenograft proliferation assays, cell death assays, conditional Melk knockout mice\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — kinome screen plus multiple functional assays, highly cited\",\n      \"pmids\": [\"24844244\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Crystal structure of MPK38/MELK (T167E active mutant) in complex with the MELK-selective inhibitor OTSSP167 was determined, revealing detailed protein-inhibitor interactions at the active site.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure of MELK-inhibitor complex\",\n      \"pmids\": [\"24657156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"EZH2 is targeted by the MELK-FOXM1 complex in glioma stem cells, promoting radiation resistance; the MELK-EZH2 axis is evolutionarily conserved in C. elegans. MELK or FOXM1 loss reduces EZH2 activity and sensitizes GSCs to radiation.\",\n      \"method\": \"Gain- and loss-of-function (shRNA, overexpression), C. elegans genetic analysis, correlation in clinical GBM samples\",\n      \"journal\": \"Stem cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell/organism models with defined mechanism, cross-species conservation\",\n      \"pmids\": [\"25601206\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MELK phosphorylates eIF4B at Ser406 during mitosis; this MELK-eIF4B signaling axis regulates protein synthesis specifically during mitosis, including synthesis of the anti-apoptotic protein MCL1. Inactivation of MELK or eIF4B reduces MCL1 protein synthesis and induces apoptotic cell death in cancer cells.\",\n      \"method\": \"Immunoprecipitation/mass spectrometry, peptide library profiling, in vitro kinase assay, protein synthesis measurement, Western blotting, siRNA knockdown\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — IP/MS substrate identification combined with in vitro kinase assay and functional cellular validation\",\n      \"pmids\": [\"27528663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MELK inhibition (genetic and pharmacological) reduces DNA damage repair, sensitizing breast cancer cells to radiation; MELK knockdown was associated with impaired γH2AX clearance after radiation in vitro and delayed tumor growth after irradiation in vivo.\",\n      \"method\": \"shRNA knockdown, γH2AX staining, clonogenic survival assay, xenograft irradiation model\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple methods but primarily phenomenological; single lab\",\n      \"pmids\": [\"27225691\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MELK is transcriptionally upregulated by MAPK pathway via transcription factor E2F1 in melanoma cells. MELK promotes melanoma growth by activating NF-κB pathway activity via Sequestosome 1 (SQSTM1/p62); SILAC phosphoproteomic analysis identified 469 proteins with reduced phosphorylation after MELK inhibition, including 139 BRAF/MEK substrates.\",\n      \"method\": \"SILAC phosphoproteomics, shRNA knockdown, pharmacological inhibition, NF-κB reporter assay, Western blotting\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — quantitative phosphoproteomics combined with mechanistic pathway validation\",\n      \"pmids\": [\"29212029\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MELK phosphorylates HIV-1 capsid at Ser-149 in the multimerized HIV-1 core, triggering uncoating to promote viral cDNA synthesis. A phosphorylation-mimetic substitution at Ser-149 causes premature capsid disassembly and earlier cDNA synthesis but failure to enter the nucleus.\",\n      \"method\": \"Genetic screen in human T-cells, MELK depletion, in vitro phosphorylation assay, capsid disassembly assay, HIV-1 replication assay, site-directed mutagenesis of capsid Ser-149\",\n      \"journal\": \"PLoS pathogens\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct in vitro phosphorylation with mutagenesis validation and functional cellular consequence\",\n      \"pmids\": [\"28683086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MELK inhibition induces p21 expression in a p53-independent manner; FOXO1 and FOXO3, known transcriptional regulators of p21, are phosphorylated by MELK and are involved in p21 induction after MELK inhibition.\",\n      \"method\": \"MELK inhibitor (OTS167), siRNA knockdown in p53-deficient cell lines, Western blotting, cell cycle analysis\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — indirect evidence for FOXO phosphorylation by MELK; mechanism partially characterized\",\n      \"pmids\": [\"28938528\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MELK inhibition by selective inhibitor HTH-01-091, CRISPR/Cas9 knockout, and chemical-induced protein degradation does not significantly affect cellular growth in common culture conditions of basal-like breast cancer cells, revealing selectivity issues with OTSSP167 and potential off-target effects of MELK-targeting shRNAs.\",\n      \"method\": \"CRISPR/Cas9 knockout, novel selective inhibitor HTH-01-091, chemical protein degradation (dTAG), RNAi, CRISPR interference, proliferation assay\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal genetic and chemical perturbants, directly addresses mechanistic controversy\",\n      \"pmids\": [\"28926338\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"MELK bound to and phosphorylated EZH2 in medulloblastoma stem-like cells; EZH2-mediated methylation of MELK was also induced, forming a reciprocal regulatory loop. MELK-induced EZH2 phosphorylation and EZH2-mediated MELK methylation together regulate proliferation of cancer stem-like cells.\",\n      \"method\": \"Co-immunoprecipitation, kinase assay, methylation assay, immunohistochemistry, xenograft\",\n      \"journal\": \"Molecular cancer research : MCR\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and kinase assay from single lab; reciprocal modification claim needs further validation\",\n      \"pmids\": [\"28536141\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MELK inhibition by the selective inhibitor NVS-MELK8a delays mitotic entry in cancer cells, associated with delayed activation of Aurora A, Aurora B, and CDK1. Live-cell microscopy confirmed 8a significantly lengthens G2 phase in a dose-dependent manner.\",\n      \"method\": \"MIB/MS selectivity profiling, resazurin/crystal violet growth assays, double-thymidine synchronization, Western blotting, live-cell microscopy with fluorescent PCNA\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — selective inhibitor with live-cell imaging validation; multiple orthogonal methods\",\n      \"pmids\": [\"31896573\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CRISPR/Cas9-generated MELK null mutant cancer cells of multiple types exhibit wild-type growth in vitro, under environmental stress, in the presence of cytotoxic chemotherapies, and in vivo; acute inhibition of MELK with a highly specific inhibitor also produces no specific anti-proliferative phenotype.\",\n      \"method\": \"CRISPR/Cas9 knockout in multiple cancer lines, specific MELK inhibitor, xenograft growth assay, chemotherapy combination\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — rigorous genetic knockout across multiple cancer types with chemical validation\",\n      \"pmids\": [\"29417930\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MELK mediates EZH2 stability in extranodal NK/T-cell lymphoma through site-specific phosphorylation: MELK increases EZH2 S220 phosphorylation with concomitant loss of K222 ubiquitination, preventing proteasomal degradation of EZH2. USP36 was identified as the deubiquitinating enzyme that deubiquitinates EZH2 at K222. FOXM1 was not involved in this mechanism.\",\n      \"method\": \"Quantitative mass spectrometry, MELK chemical and genetic inhibition, ubiquitination assays, Western blotting, tissue microarray\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — quantitative MS with site-specific phosphorylation and ubiquitination mapping plus functional validation\",\n      \"pmids\": [\"31434700\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MELK promotes ccRCC progression by phosphorylating PRAS40 (an inhibitory subunit of mTORC1), disrupting the interaction between PRAS40 and raptor, thereby over-activating mTORC1 signaling.\",\n      \"method\": \"Loss- and gain-of-function assays, co-immunoprecipitation, Western blotting, interaction disruption assay\",\n      \"journal\": \"Cell transplantation\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP-based mechanism; single lab, limited mutagenesis validation\",\n      \"pmids\": [\"31813279\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MPK38/MELK acts as an interacting partner and activator of p21; MPK38 phosphorylates p21 at Thr55, stimulating p21 nuclear translocation and association with PPARγ, preventing adipogenesis. MPK38 also stabilizes p21 by promoting CDK2-p21 and CDK4-p21 complex formation and reducing MDM2-p21 interaction.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, site-directed mutagenesis (T55A), nuclear fractionation, CRISPR knockin, adenoviral delivery in obese mice\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assay with site mutagenesis, CRISPR knockin validation, in vivo model\",\n      \"pmids\": [\"31097688\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"CES-1 Snail (C. elegans) represses pig-1 MELK transcription in the NSM neuroblast lineage; PIG-1 MELK acts downstream of CES-1 to promote asymmetric neuroblast division by size and along the correct axis, establishing an auto-regulatory loop through which CES-1 Snail controls its own activity.\",\n      \"method\": \"Genome-wide CES-1 ChIP-seq, genetic epistasis, transcriptional reporter assays in C. elegans\",\n      \"journal\": \"Genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genome-wide ChIP with genetic epistasis validation in established C. elegans model\",\n      \"pmids\": [\"28652378\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PIG-1 MELK (C. elegans ortholog) promotes apoptosis by phosphorylating nonmuscle myosin II, leading to cortical enrichment of myosin II prior to neuroblast division. This promotes partitioning of CES-1 Snail (an anti-apoptotic factor) away from the apoptotic daughter cell. pig-1 MELK is controlled by both a ces-1 Snail- and par-4 LKB1-dependent pathway.\",\n      \"method\": \"Genetic analysis in C. elegans, phosphorylation assay, live imaging, epistasis analysis\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis combined with biochemical phosphorylation assay, cross-validated with previous pig-1 studies\",\n      \"pmids\": [\"32946434\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MELK directly interacts with MLST8 (a component of mTOR complexes) and activates mTORC1 and mTORC2 signaling pathways in endometrial carcinoma. E2F1 transcriptionally regulates MELK expression, establishing an E2F1/MELK/mTORC1/2 axis.\",\n      \"method\": \"Co-immunoprecipitation, chromatin immunoprecipitation, luciferase reporter assay, Western blotting, xenograft model\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — Co-IP for MELK-MLST8 interaction; single lab, mechanistic follow-up limited\",\n      \"pmids\": [\"31915116\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MELK inhibition arrests LUAD cells at G2/M phase via the PLK1-CDC25C-CDK1 pathway and triggers apoptosis-mediated pyroptosis. MELK knockdown inhibits migration/invasion potentially through Twist1, Slug, MMP7, and N-catenin.\",\n      \"method\": \"MELK inhibitor OTSSP167, shRNA knockdown, cell cycle analysis, apoptosis assay, Western blotting, invasion assay\",\n      \"journal\": \"Signal transduction and targeted therapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — pathway placement by Western blot; mechanism not directly validated by mutagenesis\",\n      \"pmids\": [\"33262323\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Smad2, Smad3, and Smad4 increase MPK38/MELK-mediated ASK1/TGF-β/p53 signaling and stabilize MPK38 by attenuating its interaction with the negative regulator thioredoxin (Trx) and enhancing interaction with the positive regulator ZPR9. Smad7 has opposite effects. MPK38 phosphorylates Smads (Smad2 S245, Smad3 S204, Smad4 S343, Smad7 T96), and these phosphorylations are required for Smad effects on MPK38 activity.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, phosphorylation-defective mutants, adenoviral delivery in HFD-fed obese mice\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay with mutagenesis, in vivo validation in obese mice\",\n      \"pmids\": [\"29700281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"ZPR9 is an activator of MPK38/MELK; the MPK38-ZPR9 association is mediated by cysteine residues (Cys269/Cys286 of MPK38; Cys305/Cys308 of ZPR9). MPK38 phosphorylates ZPR9 at Thr252, and wild-type (but not T252A mutant) ZPR9 enhances ASK1, TGF-β, and p53 function by stabilizing MPK38.\",\n      \"method\": \"Co-immunoprecipitation, in vitro kinase assay, CRISPR/Cas9 knockin (ZPR9 T252A), NIH 3T3 inducible knockdown, MPK38 kinase assay\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — in vitro kinase assay with mutagenesis and CRISPR knockin validation\",\n      \"pmids\": [\"28195154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"MELK activates the PI3K/mTOR signaling pathway and subsequently promotes DLAT (dihydrolipoamide S-acetyltransferase) expression, stabilizing mitochondrial function and respiration in HCC. This reduces intracellular ROS and decreases sensitivity to the copper ionophore elesclomol (cuproptosis), promoting HCC progression.\",\n      \"method\": \"MELK knockdown/overexpression, Western blotting, mitochondrial function assays, ROS measurement, copper ionophore treatment, xenograft\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — pathway analysis by Western blot; mechanistic link between MELK and DLAT not directly established by kinase assay\",\n      \"pmids\": [\"37949877\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"MELK binds to STAT3 and induces STAT3 phosphorylation in HCC, increasing expression of CCL2. This MELK-STAT3-CCL2 axis promotes M2 macrophage polarization and inhibits CD8+ T cell recruitment, contributing to an immunosuppressive tumor microenvironment.\",\n      \"method\": \"IP-MS, co-immunoprecipitation, luciferase assay, RNA sequencing, xenograft models, flow cytometry\",\n      \"journal\": \"Molecular cancer\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — IP-MS identification with Co-IP validation and functional cellular assays; single lab\",\n      \"pmids\": [\"38970074\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"MELK binds to FABP5 and affects its ubiquitination through the K48R pathway to increase FABP5 stability, thereby activating the AKT/mTOR signaling axis and weakening RFA-mediated antitumor immune effects in HCC.\",\n      \"method\": \"RNA sequencing, co-immunoprecipitation, ubiquitination assay, nanoparticle-mediated MELK inhibition, in vivo tumor models\",\n      \"journal\": \"Military Medical Research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP with ubiquitination assay; mechanism partially characterized, single lab\",\n      \"pmids\": [\"39871325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Wild-type p53 suppresses MELK expression by inhibiting E2F1-dependent transcription of FOXM1 (which in turn drives MELK expression). Mutation/loss of p53 de-represses FOXM1-driven MELK expression. ChIP assays showed wild-type p53 reduces E2F1 binding to the FOXM1 promoter.\",\n      \"method\": \"Promoter deletion studies, ChIP assay, overexpression of wild-type p53 in p53-null cells, Western blotting, gene expression analysis\",\n      \"journal\": \"NPJ breast cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — ChIP assay combined with promoter deletion and genetic rescue experiments\",\n      \"pmids\": [\"31909186\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"MELK identified PSMA1 (proteasome subunit alpha type 1) and DBNL (drebrin-like) as novel substrates; MELK phosphorylates these substrates in vitro, and these substrates are important for stem-cell characteristics and invasiveness. OTSSP167 inhibits this phosphorylation.\",\n      \"method\": \"High-throughput screening, in vitro kinase assay with recombinant substrates, structure-activity relationship studies\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — substrate identification with kinase assay; functional consequences established indirectly\",\n      \"pmids\": [\"23283305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"MELK enhances DEPDC1 phosphorylation and its stability as a downstream molecule in the MELK signaling pathway; MELK inhibition by OTS167 reduces DEPDC1 expression in treated xenograft tumor tissues.\",\n      \"method\": \"Western blotting, in vitro kinase assay (implied), xenograft pharmacodynamic analysis\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — pharmacological evidence only; direct kinase assay on DEPDC1 not fully described in abstract\",\n      \"pmids\": [\"26918358\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MELK inhibition in DIPG reduces inhibitory phosphorylation of PPARγ, resulting in increased nuclear translocation and consequent transcriptional activity of PPARγ, identifying a MELK-PPARγ signaling axis.\",\n      \"method\": \"RNA sequencing of MELK inhibitor-treated cells, Western blotting for PPARγ phosphorylation and localization, patient-derived DIPG cultures\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — RNA-seq-guided mechanism with Western blot validation; direct kinase assay on PPARγ not demonstrated\",\n      \"pmids\": [\"30061363\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"DDX56 enhances MELK expression in HCC, and MELK in turn promotes FOXM1 expression/activity; DDX56 knockdown reduces MELK-mediated FOXM1 signaling, establishing a DDX56-MELK-FOXM1 axis regulating cancer stemness and EMT in HCC.\",\n      \"method\": \"shRNA knockdown, Western blotting, xenograft model with lung metastasis assessment\",\n      \"journal\": \"iScience\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — pathway placement by knockdown and Western blot without direct biochemical validation of mechanism\",\n      \"pmids\": [\"38827395\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MELK is a conserved Snf1/AMPK-family serine/threonine kinase whose activity is cell-cycle regulated, peaking during mitosis, where it is activated by autophosphorylation at Thr167/Ser171 and by MPF/MAPK-mediated phosphorylation; MELK promotes cell proliferation and mitotic progression through multiple substrates and effectors, including FOXM1 (direct phosphorylation and activation), eIF4B (Ser406 phosphorylation to sustain MCL1 synthesis during mitosis), EZH2 (phosphorylation at S220 to prevent ubiquitin-mediated degradation), Bcl-GL (phosphorylation to suppress pro-apoptotic activity), p21 (Thr55 phosphorylation), and PRAS40 (phosphorylation to activate mTORC1); MELK also controls spliceosome assembly through phosphorylation-dependent interaction with NIPP1, reduces replication stress in cancer cells (linked to MDMX-p53 regulation), promotes cytokinesis via association with anillin and regulation of RhoA at the division furrow, and in its C. elegans ortholog PIG-1 form, promotes apoptotic fate specification by phosphorylating nonmuscle myosin II to partition CES-1 Snail asymmetrically—while CRISPR-based studies have challenged its essentiality for basal proliferation, indicating context-dependent roles.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MELK is a cell-cycle-regulated Snf1/AMPK-family serine/threonine kinase that promotes mitotic progression, cell proliferation, and survival through phosphorylation of diverse substrates. Activated by autophosphorylation at Thr167/Ser171 and by mitotic kinases MPF and MAPK, MELK phosphorylates FOXM1 to drive mitotic gene expression, eIF4B at Ser406 to sustain MCL1 translation during mitosis, EZH2 at S220 to prevent its ubiquitin-mediated degradation, Bcl-GL to suppress apoptosis, p21 at Thr55 to regulate nuclear translocation, and Smad proteins to modulate TGF-β/p53 signaling [PMID:16216881, PMID:23404835, PMID:27528663, PMID:31434700, PMID:17280616, PMID:31097688, PMID:29700281]. MELK also inhibits spliceosome assembly through phosphorylation-dependent binding to NIPP1, participates in cytokinesis via association with anillin and regulation of RhoA at the cleavage furrow, and reduces replication stress in cancer cells [PMID:14699119, PMID:21378312, PMID:23836907]. CRISPR knockout studies across multiple cancer cell lines reveal that MELK is dispensable for basal proliferation under standard conditions, indicating context-dependent essentiality despite its prominent expression in aggressive cancers [PMID:28926338, PMID:29417930].\",\n  \"teleology\": [\n    {\n      \"year\": 1997,\n      \"claim\": \"Identification of MELK as a novel Snf1/AMPK-family kinase with a leucine zipper motif established a new kinase gene expressed in early embryonic development, opening the question of its substrate specificity and biological function.\",\n      \"evidence\": \"Differential display cloning from mouse egg/preimplantation embryo cDNA libraries with sequence analysis\",\n      \"pmids\": [\"9136115\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No substrates or cellular function identified\", \"Expression pattern limited to mouse early embryo\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Biochemical dissection revealed that MELK activation requires autophosphorylation at Thr167/Ser171, that a UBA domain is part of the minimal active fragment, and that a C-terminal domain is autoinhibitory — establishing the enzymological framework for understanding MELK regulation.\",\n      \"evidence\": \"In vitro kinase assay, mass spectrometry phosphorylation mapping, site-directed mutagenesis, domain truncation analysis\",\n      \"pmids\": [\"16216881\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream activating kinase not yet identified in mammalian cells\", \"Structural basis of autoinhibition unresolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Discovery that MELK inhibits spliceosome assembly through phosphorylation-dependent interaction with NIPP1's FHA domain revealed a non-canonical role for MELK in RNA processing, linking MELK to mitotic translational regulation.\",\n      \"evidence\": \"Recombinant protein interaction assays, in vitro spliceosome reconstitution, T478A mutagenesis, mitotic cell fractionation\",\n      \"pmids\": [\"14699119\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological relevance of splicing inhibition during mitosis not demonstrated in vivo\", \"Whether MELK kinase activity targets other spliceosome components unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identification of MELK as an E2F transcriptional target and its requirement for neural progenitor proliferation established MELK as a cell-cycle-coupled proliferative kinase in stem/progenitor cells, with B-myb as a downstream mediator.\",\n      \"evidence\": \"E2F site mutagenesis in Melk promoter, p107/p130 knockout cell analysis, siRNA knockdown and overexpression in neurosphere assays\",\n      \"pmids\": [\"16144839\", \"16061694\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation targets mediating progenitor proliferation not identified\", \"Relationship between MELK and B-myb not biochemically defined\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Mapping of mitosis-specific phosphorylation sites on Xenopus MELK by MPF and MAPK, and identification of PIG-1 (C. elegans ortholog) as a regulator of asymmetric cell division, expanded MELK's role beyond proliferation to mitotic regulation and cell fate determination.\",\n      \"evidence\": \"Xenopus M-phase extract phosphorylation mapping with in vitro kinase assays; C. elegans pig-1 mutant lineage tracing\",\n      \"pmids\": [\"16628004\", \"16774992\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mammalian equivalents of MPF/MAPK-mediated activation sites not confirmed\", \"How PIG-1 mechanistically controls cell size asymmetry unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstration that MELK phosphorylates the pro-apoptotic Bcl-GL protein and that kinase activity is required to suppress Bcl-GL-induced apoptosis established MELK as a direct anti-apoptotic kinase.\",\n      \"evidence\": \"Recombinant pull-down, immunocomplex kinase assay with kinase-dead D150A mutant, TUNEL/FACS apoptosis assays\",\n      \"pmids\": [\"17280616\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Bcl-GL phosphorylation site not mapped\", \"In vivo relevance of MELK-Bcl-GL axis not tested\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Localization of Xenopus MELK to the cleavage furrow and its interaction with anillin, combined with overexpression-induced loss of RhoA accumulation, established a direct role for MELK in cytokinesis.\",\n      \"evidence\": \"Morpholino knockdown, live imaging, co-immunoprecipitation with anillin, RhoA localization in Xenopus embryo\",\n      \"pmids\": [\"21378312\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MELK directly phosphorylates anillin or RhoA regulators unknown\", \"Mammalian cytokinesis role not confirmed\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Genetic epistasis in C. elegans placed PIG-1/MELK downstream of PAR-4/LKB1 in asymmetric neuroblast division, with activation loop T169 phosphorylation essential, establishing a conserved LKB1-MELK kinase cascade controlling cell polarity.\",\n      \"evidence\": \"Genetic epistasis with par-4/strd-1/mop-25.2, T169A mutagenesis, GFP localization in C. elegans\",\n      \"pmids\": [\"23267054\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation of PIG-1 by PAR-4 not biochemically demonstrated\", \"Whether mammalian LKB1 activates MELK in vivo not shown\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Multiple studies converged to identify FOXM1 as a direct MELK substrate in glioma stem cells, established that MELK loss causes replication stress and p53-dependent cell cycle arrest, and resolved the MELK crystal structure — collectively defining MELK as a mitotic kinase hub linking DNA integrity, transcription, and structural drug design.\",\n      \"evidence\": \"Co-IP/kinase assay for FOXM1; DNA fiber assay and γH2AX for replication stress; X-ray crystallography of MELK-AMP-PNP and inhibitor complexes\",\n      \"pmids\": [\"23404835\", \"23836907\", \"23914841\", \"23339114\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"FOXM1 phosphorylation sites by MELK not mapped\", \"How MELK prevents replication stress mechanistically unclear\", \"Whether MELK-JUN complex is direct or scaffolded unknown\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"A kinome-wide screen identified MELK as an oncogenic kinase selectively required in basal-like breast cancer (BBC), with FOXM1 driving its transcription, suggesting a FOXM1-MELK positive feedback loop in aggressive breast cancer subtypes.\",\n      \"evidence\": \"ORF kinome screen, shRNA knockdown, xenograft proliferation, conditional Melk knockout mice\",\n      \"pmids\": [\"24844244\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of basal-like selectivity not defined\", \"Direct evidence for positive feedback loop incomplete\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Identification of eIF4B Ser406 as a direct mitotic MELK substrate controlling MCL1 protein synthesis revealed how MELK sustains anti-apoptotic protein levels specifically during mitosis, linking MELK to translational control.\",\n      \"evidence\": \"IP/MS substrate identification, peptide library profiling, in vitro kinase assay, protein synthesis measurement\",\n      \"pmids\": [\"27528663\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other mRNAs are translationally regulated by MELK-eIF4B unknown\", \"In vivo validation of eIF4B-MCL1 axis not performed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"CRISPR knockout, chemical degradation, and highly selective inhibitors revealed that MELK is dispensable for basal proliferation of breast cancer cells under standard conditions, challenging prior RNAi-based essentiality claims and demonstrating off-target effects of OTSSP167.\",\n      \"evidence\": \"CRISPR/Cas9 knockout, selective inhibitor HTH-01-091, dTAG chemical degradation, proliferation assays in multiple BBC lines\",\n      \"pmids\": [\"28926338\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Context-specific conditions under which MELK becomes essential not systematically defined\", \"Whether MELK is essential in vivo under stress or immune challenge not addressed\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Phosphoproteomic analysis in melanoma linked MELK to MAPK/E2F1 transcriptional control and NF-κB activation via SQSTM1/p62, while studies of Smad phosphorylation and ZPR9 activation expanded MELK's signaling network to TGF-β and ASK1 pathways.\",\n      \"evidence\": \"SILAC phosphoproteomics; Co-IP and in vitro kinase assays with Smad and ZPR9 phosphorylation-defective mutants; CRISPR knockin of ZPR9 T252A\",\n      \"pmids\": [\"29212029\", \"29700281\", \"28195154\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How MELK activates NF-κB via p62 mechanistically unresolved\", \"Smad-MELK axis validated primarily in adipogenesis context\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Confirmation that CRISPR-null MELK cancer cells grow normally across multiple cancer types and conditions, combined with evidence that selective MELK inhibition delays mitotic entry via delayed Aurora A/B and CDK1 activation, refined the view that MELK is not a general cancer dependency but does regulate G2/M timing.\",\n      \"evidence\": \"CRISPR knockout in multiple cancer lines with xenograft; selective inhibitor NVS-MELK8a with live-cell PCNA imaging and synchronization\",\n      \"pmids\": [\"29417930\", \"31896573\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which MELK regulates Aurora/CDK1 activation not biochemically defined\", \"Whether genetic compensation masks MELK loss in knockouts not tested\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Direct phosphorylation of EZH2 at S220 by MELK was shown to prevent K222 ubiquitination and proteasomal degradation (with USP36 as the deubiquitinase), establishing a site-specific mechanism for MELK-dependent EZH2 stabilization distinct from FOXM1-mediated effects.\",\n      \"evidence\": \"Quantitative mass spectrometry, ubiquitination assays, MELK chemical and genetic inhibition in NK/T-cell lymphoma\",\n      \"pmids\": [\"31434700\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MELK directly phosphorylates EZH2 or acts through an intermediate kinase not fully excluded\", \"Generalizability beyond NK/T-cell lymphoma not established\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"MELK was shown to phosphorylate p21 at Thr55, promoting nuclear translocation, CDK complex formation, and association with PPARγ to inhibit adipogenesis, revealing a metabolic regulatory function for MELK beyond cancer.\",\n      \"evidence\": \"In vitro kinase assay, T55A mutagenesis, CRISPR knockin, adenoviral delivery in obese mice\",\n      \"pmids\": [\"31097688\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether Thr55 phosphorylation of p21 by MELK occurs in cancer contexts not shown\", \"Relative contribution of MELK vs. other Thr55 kinases in vivo unknown\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"C. elegans studies established that PIG-1/MELK promotes apoptotic fate by phosphorylating nonmuscle myosin II to partition CES-1 Snail asymmetrically, within an autoregulatory circuit where CES-1 represses pig-1 transcription, providing a complete mechanistic model for MELK-driven asymmetric cell fate.\",\n      \"evidence\": \"ChIP-seq for CES-1, genetic epistasis, phosphorylation assay, live imaging in C. elegans\",\n      \"pmids\": [\"28652378\", \"32946434\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mammalian MELK phosphorylates myosin II or controls asymmetric division similarly is unknown\", \"Structural basis of PIG-1-myosin II interaction not determined\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"MELK was linked to tumor immune evasion through STAT3 phosphorylation driving CCL2 expression and M2 macrophage polarization, and to FABP5 stabilization activating AKT/mTOR, expanding MELK's roles to immunomodulation in hepatocellular carcinoma.\",\n      \"evidence\": \"IP-MS and Co-IP for STAT3; Co-IP and ubiquitination assay for FABP5; xenograft models with immune profiling\",\n      \"pmids\": [\"38970074\", \"39871325\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether MELK directly phosphorylates STAT3 or FABP5 not shown by in vitro kinase assay\", \"Immunomodulatory role not validated in immunocompetent genetic models\", \"Single-lab findings for each axis\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unresolved under which physiological or pathological conditions MELK becomes essential, given that CRISPR knockouts show no proliferative defect; whether genetic compensation or context-dependent stress unmasks MELK dependence is a central open question.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conditions conferring MELK essentiality not systematically identified\", \"No comprehensive interactome under stress conditions\", \"In vivo immune-competent models of MELK loss largely absent\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [2, 7, 10, 18, 21, 27, 29, 34, 35]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [2, 6, 7, 18, 21, 27, 29, 34]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 28, 32]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 18]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [8, 14]},\n      {\"term_id\": \"GO:0005815\", \"supporting_discovery_ids\": [9]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [29]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [4, 6, 8, 15, 18, 25]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [7, 18, 31]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [20, 28, 32, 34, 37]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [3, 10, 39]},\n      {\"term_id\": \"R-HSA-8953854\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [18, 27]}\n    ],\n    \"complexes\": [\n      \"MELK-FOXM1 complex\",\n      \"MELK-NIPP1 complex\"\n    ],\n    \"partners\": [\n      \"FOXM1\",\n      \"EZH2\",\n      \"NIPP1\",\n      \"ANLN\",\n      \"eIF4B\",\n      \"ZPR9\",\n      \"STAT3\",\n      \"MLST8\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}