{"gene":"MAP3K1","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":1994,"finding":"MEKK1 (MAP3K1) phosphorylates and activates SEK1 (MKK4), which in turn phosphorylates and activates SAPK/JNK stress-activated protein kinases, defining MEKK1 as a MAP3K in the JNK signaling cascade.","method":"In vitro kinase assay; expression in COS-7 cells and NIH3T3 inducible cell lines","journal":"Nature","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution of kinase cascade, replicated across multiple cell systems, >700 citations","pmids":["7997270"],"is_preprint":false},{"year":1997,"finding":"MEKK1 is cleaved by caspase 3 (CPP32) after residue D68 in response to Fas ligation; this cleavage is required for MEKK1 kinase activation and redistributes MEKK1 from a Triton-insoluble (particulate) compartment to a Triton-soluble (diffuse cytoplasmic) compartment.","method":"Sequencing of proteolytic cleavage products; in vitro and in vivo caspase cleavage assays; immunofluorescence; subcellular fractionation; viral and chemical caspase inhibitors","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — direct identification of cleavage site by sequencing, in vivo and in vitro validation, multiple orthogonal methods","pmids":["9576928"],"is_preprint":false},{"year":1997,"finding":"MEKK1 binds directly to the N-terminal non-catalytic domain of JNK/SAPK in vitro and in transfected cells; this interaction facilitates JNK activation by MEKK1.","method":"In vitro binding with immobilized MEKK1-derived peptides; co-immunoprecipitation in transfected cells; selective extraction from cell lysates","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — direct in vitro binding confirmed by reciprocal co-IP and peptide pulldown","pmids":["9405400"],"is_preprint":false},{"year":1997,"finding":"MEKK1 autophosphorylates on Thr-575 within its activation loop (between kinase subdomains VII and VIII), and this autophosphorylation is required for full kinase activity; mutation of Thr-587 to alanine eliminates substrate (MEK/SEK) phosphorylation but not autophosphorylation.","method":"Site-directed mutagenesis; in vitro kinase assay; phosphatase treatment; metabolic labeling","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 — in vitro kinase assays with mutagenesis, identified specific autophosphorylation sites","pmids":["9078260"],"is_preprint":false},{"year":1997,"finding":"Caspase cleavage of MEKK1 is required for its activation during anoikis; the MEKK1 cleavage product stimulates apoptosis, and a cleavage-resistant MEKK1 mutant partially protects cells from anoikis, establishing a caspase–MEKK1 positive feedback loop.","method":"Overexpression of MEKK1 cleavage product and cleavage-resistant mutant; caspase activity assays; anoikis functional assays","journal":"Cell","confidence":"High","confidence_rationale":"Tier 1–2 — mutant rescue and loss-of-function in defined cellular apoptosis model, >460 citations","pmids":["9244305"],"is_preprint":false},{"year":1998,"finding":"MEKK1 activates the MEKK1-JNK signaling axis to stabilize p53 by reducing its ubiquitination; JNK phosphorylates p53, which abolishes MDM2 binding and prevents p53 ubiquitination, leading to increased p53 transcriptional activity and apoptosis.","method":"Expression of constitutively active ΔMEKK1; in vivo ubiquitination assay; in vitro phosphorylation of p53 by immunopurified JNK; co-immunoprecipitation of p53-MDM2; luciferase reporter assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal biochemical methods in a single study","pmids":["9724739"],"is_preprint":false},{"year":1998,"finding":"MEKK1 suppresses NF-AT4 nuclear import by stabilizing the interaction between NF-AT4 and casein kinase Iα (CKIα), which phosphorylates NF-AT4 and causes intramolecular masking of its nuclear localization signal.","method":"Identification of CKIα as NF-AT4 binding partner; co-immunoprecipitation; nuclear import assays; phosphorylation assays","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP and functional nuclear import assay, >260 citations","pmids":["9630228"],"is_preprint":false},{"year":1999,"finding":"MEKK1 is required for JNK activation in response to microtubule toxins (taxol) but not actin fiber disruption; MEKK1-deficient embryonic stem cells fail to activate JNK and show increased apoptosis in response to taxol, while MEKK2 disruption has no effect.","method":"Targeted gene disruption (MEKK1-/- ES cells); JNK kinase assay; apoptosis assay; cell cycle analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — clean KO with specific pathway readout, genetic specificity confirmed by MEKK2 KO comparison","pmids":["10212239"],"is_preprint":false},{"year":1999,"finding":"MEKK1 interacts with the actin-crosslinking protein α-actinin via residues 221–559 in its N-terminal domain, and both endogenous and overexpressed MEKK1 co-localize with α-actinin along actin stress fibers and at focal adhesions; kinase activity is not required for this localization.","method":"Yeast two-hybrid screen; co-immunoprecipitation; in vitro binding with purified α-actinin; immunofluorescence co-localization; kinase-inactive mutant","journal":"Cell motility and the cytoskeleton","confidence":"High","confidence_rationale":"Tier 2 — direct in vitro binding confirmed, subcellular localization validated by immunofluorescence with kinase-dead mutant","pmids":["10401575"],"is_preprint":false},{"year":1999,"finding":"MEKK1 deficiency in embryonic stem cell-derived cardiac myocytes abolishes JNK activation but not p38 activation in response to oxidative stress (H2O2); the MEKK1-JNK pathway protects against apoptosis by suppressing TNF-α production.","method":"Targeted MEKK1 gene disruption in ES cells; JNK and p38 kinase assays; TNF-α measurement; apoptosis assay","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — clean KO with multiple pathway readouts and defined cytokine mechanism","pmids":["10611349"],"is_preprint":false},{"year":2000,"finding":"MEKK1 binds directly to ERK2, MEK1, and Raf-1 via its N-terminal regulatory domain, demonstrating that MEKK1 can scaffold the entire ERK MAP kinase module.","method":"Co-immunoprecipitation of endogenous proteins","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP of endogenous proteins but single-lab, single method","pmids":["10969079"],"is_preprint":false},{"year":2000,"finding":"Raf-mediated NF-κB activation requires MEKK1 as a membrane shuttle kinase; a dominant-negative MEKK1 blocks Raf- and PMA-induced NF-κB activation, which depends on IKK-2 but not the classical MEK-ERK cascade.","method":"Dominant-negative MEKK1 expression; NF-κB reporter assay; IKK activity assay; pharmacological inhibitors","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2–3 — dominant-negative plus pathway-specific inhibitors, single lab","pmids":["10758165"],"is_preprint":false},{"year":2001,"finding":"The PHD/RING finger-like domain of MEKK1 functions as an E3 ubiquitin ligase that ubiquitinates ERK1/2, promoting their proteasome-dependent degradation during stress; both MEKK1 kinase activity and a docking motif on ERK1/2 are required for ERK ubiquitination.","method":"In vitro ubiquitin ligase assay; in vivo ubiquitination; docking motif mutations on ERK2; apoptosis assay in ERK2 docking mutant cells","journal":"Molecular cell","confidence":"High","confidence_rationale":"Tier 1 — in vitro reconstitution of E3 ligase activity with mutagenesis and in vivo validation, >260 citations","pmids":["12049732"],"is_preprint":false},{"year":2002,"finding":"Caspase-generated 91-kDa MEKK1 kinase fragment relocalizes from a particulate fraction to a soluble cytoplasmic fraction; this relocalization (not JNK, ERK, NF-κB, or p300 activation) is necessary for MEKK1's pro-apoptotic function.","method":"Subcellular fractionation; membrane-targeting signal added to 91-kDa fragment; caspase activation assays; kinase activity assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — direct manipulation of localization with functional consequence, multiple orthogonal readouts","pmids":["11782455"],"is_preprint":false},{"year":2002,"finding":"MEKK1 mediates pressure overload-induced JNK activation in the heart; MEKK1-deficient mice show loss of JNK activation after aortic banding while cardiac hypertrophy still occurs, indicating MEKK1 is required for JNK activation but not hypertrophy. MEKK1 protects against apoptosis and inflammation under pressure overload.","method":"MEKK1 knockout mice; aortic banding model; JNK activity assay; cardiac morphometry; apoptosis assay","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — in vivo KO with defined pathway readout, multiple physiological endpoints","pmids":["12122119"],"is_preprint":false},{"year":2002,"finding":"MEKK1 is essential for Gαq-induced cardiac hypertrophy; MEKK1 knockout abolishes JNK activation, cardiac mass increase, myocyte hypertrophy, and ANF induction by Gαq, while improving ventricular function.","method":"MEKK1 knockout ES cell-derived cardiac myocytes; Gαq-overexpressing transgenic mice crossed with MEKK1-/- mice; JNK kinase assay; echocardiography; ANF expression","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — in vitro and in vivo KO with multiple specific pathway and phenotypic readouts","pmids":["11891332"],"is_preprint":false},{"year":2002,"finding":"Receptor-interacting protein (RIP) physically associates with and phosphorylates MEKK1 at Ser-957 and Ser-994, thereby activating MEKK1; this RIP-MEKK1 interaction mediates TNF-α-induced IKKβ/NF-κB activation.","method":"In vitro binding; co-immunoprecipitation; in vitro kinase assay (RIP phosphorylation of MEKK1); phosphorylation-site mutants; RIP-deficient Jurkat cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro kinase assay identifying specific phosphorylation sites with mutagenesis and KO cell validation","pmids":["11369754"],"is_preprint":false},{"year":2002,"finding":"PAK1 phosphorylates MEKK1 on Ser-67 within a D domain that mediates JNK/SAPK binding; constitutive Ser-67 phosphorylation in resting cells inhibits JNK binding to MEKK1, and stress stimuli cause dephosphorylation of Ser-67 to allow JNK binding.","method":"In vitro kinase assay (PAK1 phosphorylation of MEKK1 N-terminus); phosphorylation-site mutants; co-immunoprecipitation; phospho-specific analysis in stressed cells","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — identification of specific phosphorylation site by kinase assay with mutagenesis and in-cell validation","pmids":["12228228"],"is_preprint":false},{"year":2003,"finding":"RhoA (but not Rac or Cdc42) binds to the N-terminal one-third of MEKK1 including its PHD domain; RhoA-GTP stimulates MEKK1 kinase activity up to 10-fold toward MEK4, and mutation of the essential PHD cysteine prevents RhoA interaction.","method":"In vitro binding assay; co-immunoprecipitation; in vitro kinase assay; PHD domain mutagenesis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — direct in vitro binding and kinase stimulation with mutagenesis","pmids":["14581471"],"is_preprint":false},{"year":2003,"finding":"MEKK1 is required for inducible urokinase-type plasminogen activator (uPA) expression; MEKK1-deficient fibroblasts show greatly reduced uPA expression/activity in response to PMA or FGF-2, dependent on MEKK1-driven MKK1 and JNK activity; MEKK2 disruption has no effect.","method":"MEKK1 knockout fibroblasts; rescue by MEKK1 transfection; uPA activity assay; genetic specificity via MEKK2 disruption","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — KO with rescue, genetic specificity confirmed by MEKK2 comparison","pmids":["12493778"],"is_preprint":false},{"year":2003,"finding":"MEKK1 activity drives formation of polyglutamine-containing inclusion bodies by recruiting polyQ-containing huntingtin fragments into a particulate/insoluble fraction; kinase-dead MEKK1 cannot stimulate inclusion body formation.","method":"Overexpression of active vs. kinase-dead MEKK1; cellular fractionation; fluorescence microscopy of huntingtin-GFP inclusion bodies","journal":"The Journal of cell biology","confidence":"Medium","confidence_rationale":"Tier 2–3 — kinase-dead mutant comparison with fractionation, single lab","pmids":["11352944"],"is_preprint":false},{"year":2004,"finding":"Ceramide directly binds MEKK1 (but not c-Raf) in glomerular endothelial cells, as demonstrated by photoaffinity labeling and ceramide-sepharose affinity chromatography, leading to SAPK/JNK cascade activation.","method":"Radioiodinated photoaffinity ceramide analogue labeling; ceramide-sepharose affinity chromatography; JNK/SEK phosphorylation assays","journal":"Biochimica et biophysica acta","confidence":"Medium","confidence_rationale":"Tier 2 — direct binding demonstrated by two independent methods (photoaffinity + affinity chromatography), single lab","pmids":["15164763"],"is_preprint":false},{"year":2004,"finding":"Glutathione S-transferase Mu 1-1 (GST M1-1) directly binds MEKK1, inhibits its kinase activity in a catalysis-independent manner, and interferes with MEKK1-SEK1 interaction, thereby suppressing MEKK1-induced apoptosis.","method":"In vitro binding assay; in vitro kinase assay; co-immunoprecipitation of endogenous proteins; binding competition assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — in vitro binding and kinase assays with co-IP of endogenous proteins, single lab","pmids":["15299005"],"is_preprint":false},{"year":2006,"finding":"The PHD/RING finger domain of MEKK1 acts as an E3 ubiquitin ligase toward c-Jun in response to osmotic stress; MEKK1 ubiquitinates and degrades c-Jun in vitro and in vivo, and MEKK1-/- cells have elevated c-Jun levels. c-Jun downregulation by MEKK1 promotes apoptosis.","method":"In vitro ubiquitin ligase assay; in vivo ubiquitination; MEKK1-/- cells; apoptosis assay with c-Jun overexpression","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1 — in vitro E3 ligase reconstitution confirmed in vivo with KO cells","pmids":["17101801"],"is_preprint":false},{"year":2006,"finding":"MEKK1 controls tumor cell dissemination and lung metastasis in PyMT mammary cancer by regulating urokinase-type plasminogen activator (uPA) expression, gelatinase activity, and basement membrane integrity; MEKK1-/- tumors show markedly reduced uPA, reduced cell migration and invasion.","method":"MEKK1-/- mice crossed with PyMT transgenic; in vivo metastasis assay; uPA expression and activity; gelatinase zymography; siRNA knockdown in MDA-MB-231 cells; invasion assays","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 — in vivo KO plus siRNA knockdown with multiple mechanistic readouts","pmids":["16568086"],"is_preprint":false},{"year":2006,"finding":"DJ-1 directly binds and inhibits MEKK1 kinase activity through its C-terminus, sequesters MEKK1 in the cytoplasm; the pathogenic DJ-1 L166P mutant cannot associate with MEKK1 and allows MEKK1 nuclear translocation, sensitizing cells to UV-induced MEKK1-SEK1-JNK1-mediated cell death.","method":"Co-immunoprecipitation; in vitro kinase assay; subcellular fractionation; immunofluorescence; DJ-1 knockdown; L166P mutant analysis","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 — direct binding, kinase inhibition, and localization with pathogenic mutant validation","pmids":["18309325"],"is_preprint":false},{"year":2006,"finding":"MEKK1 regulates the AP-1 transcription factor repertoire by suppressing JunB mRNA expression and by inducing Fra-2 ubiquitination and degradation; loss of MEKK1 results in elevated JunB that forms an inhibitory AP-1 complex suppressing uPA transcription.","method":"MEKK1-/- cells; RT-PCR for JunB mRNA; Fra-2 ubiquitination assay; AP-1 reporter assay; uPA promoter analysis","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2–3 — KO phenotype combined with ubiquitination assay and reporter readout, single lab","pmids":["15558021"],"is_preprint":false},{"year":2007,"finding":"MEKK1 mediates eyelid closure morphogenesis through differential phosphorylation of JNK1 and JNK2; JNK1 (possessing unique Gly177 and Ser179 residues) is phosphorylated more efficiently than JNK2 by the MEKK1-MKK4 pathway activated by activin B, controlling downstream c-Jun phosphorylation and PAI1 expression.","method":"Mekk1/Jnk1/Jnk2 compound mutant mice; JNK phosphorylation assays; c-Jun phosphorylation; PAI1 expression; eyelid closure phenotype scoring","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — genetic epistasis with compound mutants plus biochemical pathway analysis","pmids":["18032450"],"is_preprint":false},{"year":2007,"finding":"STK38 (NDR kinase) physically interacts with the catalytic domain of MEKK1 and negatively regulates MEKK1 activity by converting it from its phosphorylated to non-phosphorylated form, suppressing MEKK1 autophosphorylation and downstream signaling.","method":"Co-immunoprecipitation; in vitro kinase assay; shRNA knockdown of STK38; autophosphorylation assay","journal":"Oncogene","confidence":"Medium","confidence_rationale":"Tier 2–3 — direct interaction with kinase assay and RNAi validation, single lab","pmids":["17906693"],"is_preprint":false},{"year":2008,"finding":"TRAF6 and MEKK1 act downstream of IPS-1 in the RIG-I/MDA5 antiviral pathway; MEKK1 (but not TAK1) is required for IFN-β induction in response to poly(I:C) and VSV, and co-expression of MEKK1 with IRF3 is sufficient to induce IFN-β.","method":"TRAF6-/- and TAK1-/- MEFs; siRNA knockdown of MEKK1; overexpression of MEKK1+IRF3; NF-κB, JNK, p38 activation assays; IFN-β reporter assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — KO and KD with overexpression rescue and defined pathway placement","pmids":["18984593"],"is_preprint":false},{"year":2010,"finding":"Mutations in MAP3K1 causing 46,XY disorders of sex development (DSD) alter phosphorylation of downstream targets p38 and ERK1/2, and enhance binding of RHOA to the MAP3K1 complex in patient-derived lymphoblastoid cells, implicating MAP3K1 in testis determination via MAPK signaling.","method":"Linkage analysis; sequencing of patient samples; phospho-p38 and phospho-ERK1/2 assays in patient lymphoblastoid cells; co-immunoprecipitation for RHOA binding","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 — patient mutations validated by functional biochemistry in primary cells, multiple families","pmids":["21129722"],"is_preprint":false},{"year":2010,"finding":"MAP3K1 functionally interacts with Axin1; this interaction is induced by Wnt stimulation; MAP3K1's E3 ubiquitin ligase activity (but not kinase activity) is required for TCF/LEF-driven transcription and Wnt target gene expression.","method":"Immunoprecipitation-coupled proteomics; co-immunoprecipitation with Wnt stimulation; siRNA knockdown; ubiquitin ligase mutant and kinase mutant expression; TCF/LEF luciferase reporter assay","journal":"Biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — proteomics-identified interaction validated biochemically with domain-specific mutants separating kinase from E3 ligase function","pmids":["20128690"],"is_preprint":false},{"year":2010,"finding":"MAP3K1 mutations causing 46,XY DSD enhance binding of RHOA, MAP3K4, and FRAT1 while reducing RAC1 binding; these mutations tilt signaling toward WNT/β-catenin/FOXL2 and away from SOX9/FGF9 pathways; overexpressing RHOA or reducing MAP3K4 phenocopies the mutations.","method":"Transfection of wild-type and mutant MAP3K1 in NT2/D1 cells; co-immunoprecipitation; phosphorylation assays; siRNA knockdown of RHOA/MAP3K4; reporter assays for WNT/β-catenin and SOX9/FGF9","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods; gain-of-function, phenocopy and anti-phenocopy experiments","pmids":["24135036"],"is_preprint":false},{"year":2010,"finding":"MEKK1 activation by IL-1β mediates canonical NF-κB pathway activation, which is required for IL-1β-induced increase in intestinal tight junction permeability; MEKK1 also plays an essential role in MLCK gene activation downstream of IL-1β.","method":"siRNA knockdown of MEKK1 and NIK in Caco-2 monolayers; transepithelial resistance measurement; NF-κB pathway activation assays; MLCK promoter assay","journal":"The American journal of pathology","confidence":"Medium","confidence_rationale":"Tier 2–3 — siRNA knockdown with functional barrier assay and pathway readouts, single lab","pmids":["21048223"],"is_preprint":false},{"year":2011,"finding":"MAP3K1 deficiency leads to increased proliferation, apoptosis, and Müller glial overproduction in developing retinas; this retinal defect is independent of the eye-open-at-birth phenotype and of JNK, but involves cyclin D1/CDK4/6-RB-E2F signaling.","method":"Map3k1 knockout mice; BrdU incorporation; TUNEL apoptosis assay; immunostaining for cell-type markers; compound mutant analysis with Jnk1-/- and Jnk1/2 hemizygotes; tarsorrhaphy control","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 — KO with epistasis analysis using compound mutants and surgical controls","pmids":["21862560"],"is_preprint":false},{"year":2005,"finding":"MEKK1 controls neurite regrowth after injury by simultaneously activating both ERK1/2 (via MEK1) and JNK2 (via MKK7); MEK1 and MKK7 compete for binding to MEKK1, creating a pathway cross-talk. RNAi knockdown of MEKK1 abolishes both ERK and JNK phosphorylation.","method":"RNAi knockdown; co-immunoprecipitation of MEK1 and MKK7 with MEKK1; ERK/JNK phosphorylation assays; neurite regrowth assay in PC12 cells","journal":"Molecular and cellular neurosciences","confidence":"Medium","confidence_rationale":"Tier 2–3 — RNAi with co-IP of competing substrates, single lab","pmids":["16006144"],"is_preprint":false},{"year":2003,"finding":"Axin binds MEKK1 to activate JNK; Axin also binds MEKK4 at a distinct domain, and MEKK4 can mediate Axin-induced JNK activation in MEKK1-/- cells; MEKK1 and MEKK4 compete for Axin binding.","method":"Co-immunoprecipitation; MEKK1-/- MEFs; siRNA against MEKK4; JNK activation assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — KO cells with siRNA epistasis and co-IP, single lab","pmids":["12878610"],"is_preprint":false},{"year":2002,"finding":"p115 Rho GTPase-activating protein (p115 RhoGAP) binds to the N-terminal regulatory domain of MEKK1 via the RhoGAP SH3 domain; this interaction reduces MEKK1-induced AP-1 signaling, linking MEKK1 to cytoskeletal Rho regulation.","method":"Yeast two-hybrid screen; in vitro binding; co-immunoprecipitation; AP-1 reporter assay; SH3 deletion mutant","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2–3 — yeast two-hybrid confirmed by in vitro and co-IP binding with functional reporter assay","pmids":["12115726"],"is_preprint":false},{"year":2007,"finding":"Dietary isothiocyanates (ITCs) directly and covalently modify a specific cysteine residue in the ATP binding pocket of MEKK1, irreversibly inhibiting its kinase activity; this correlates with specific inhibition of SAPK/JNK but not parallel MAPK pathways.","method":"In vitro kinase assay; affinity reagent for ITC modification; cysteine-mutant MEKK1; kinase assay of endogenous immunopurified MEKK1; phospho-specific immunoblotting","journal":"BMC cancer","confidence":"High","confidence_rationale":"Tier 1 — direct covalent modification identified with specific residue, in vitro and in vivo confirmed","pmids":["17894894"],"is_preprint":false},{"year":2018,"finding":"MAP3K1 deficiency in PIK3CA-mutant breast cancer cells enhances AKT phosphorylation and downstream signaling by impairing MAP3K1-JNK signaling that normally promotes IRS-1 degradation; MAP3K1 loss increases IRS-1 stability and IRS-1/p85 binding, enhancing PI3Kα activity.","method":"CRISPR knockout of MAP3K1; phospho-AKT/IRS-1 immunoblotting; co-immunoprecipitation of IRS-1/p85; 3D acinar growth assay; in vivo xenograft efficacy studies","journal":"Oncotarget","confidence":"High","confidence_rationale":"Tier 2 — CRISPR KO with multiple mechanistic readouts, in vitro and in vivo validation","pmids":["29765551"],"is_preprint":false},{"year":2019,"finding":"MAP3K1 mutations causing 46,XY DSD cluster in three structural domains: an N-terminal GEF-homology domain (Met164–Glu231), PHD domain (Met442–Trp495), and ARMadillo repeat domain (Met566–Glu862); mutations differentially increase binding of RHOA, MAP3K4, and FRAT1 and decrease RAC1 binding depending on domain location.","method":"Structural modeling; co-immunoprecipitation for binding partners; downstream phosphorylation assays; patient mutation functional analysis","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2–3 — co-IP binding studies with structural modeling, mechanistic follow-up on domain-specific mutations","pmids":["30608580"],"is_preprint":false}],"current_model":"MAP3K1 (MEKK1) is a dual-function MAP3K that activates the JNK/SAPK pathway by phosphorylating SEK1/MKK4 (and MKK7), activates ERK1/2 via MEK1, and regulates NF-κB; it scaffolds these cascades through its large N-terminal domain that binds JNK, ERK2, MEK1, Raf-1, α-actinin, RhoA, and Axin, while its PHD/RING finger domain acts as an E3 ubiquitin ligase toward ERK1/2, c-Jun, and Fra-2; it is activated by caspase-3/7 cleavage (releasing an active 91-kDa fragment that redistributes to the cytosol to drive apoptosis), by RIP-mediated phosphorylation at Ser-957/994 downstream of TNF-α, and by autophosphorylation at Thr-575; it is negatively regulated by PAK1 phosphorylation of Ser-67, by GST M1-1 and STK38 binding, and by DJ-1-mediated cytoplasmic sequestration; in sex determination, gain-of-function mutations shift signaling toward WNT/β-catenin/FOXL2 at the expense of SOX9/FGF9 by altering RHOA, MAP3K4, and RAC1 binding, causing 46,XY gonadal dysgenesis."},"narrative":{"teleology":[{"year":1994,"claim":"Establishing MAP3K1 as a MAP3K in the JNK cascade resolved the identity of the kinase upstream of SEK1/MKK4 in stress signaling, placing MEKK1 at the apex of a three-tiered kinase module.","evidence":"In vitro kinase assay and COS-7/NIH3T3 expression showing MEKK1 phosphorylates SEK1 which activates SAPK/JNK","pmids":["7997270"],"confidence":"High","gaps":["Whether MEKK1 also phosphorylates other MKKs (e.g., MKK7, MEK1) was not addressed","Physiological stimuli activating MEKK1 were unknown"]},{"year":1997,"claim":"Identifying caspase-3 cleavage at Asp-68 and autophosphorylation at Thr-575 revealed two distinct activation mechanisms — proteolytic release of an active kinase fragment during apoptosis and autophosphorylation-dependent catalytic competence — establishing how MEKK1 integrates apoptotic and stress signals.","evidence":"Sequencing of cleavage products, in vitro/in vivo caspase assays, subcellular fractionation, site-directed mutagenesis of autophosphorylation sites","pmids":["9576928","9078260","9244305"],"confidence":"High","gaps":["Whether other caspases (e.g., caspase-7) also cleave MEKK1 was not fully defined","The phosphatase reversing Thr-575 autophosphorylation was not identified"]},{"year":1997,"claim":"Demonstrating direct JNK binding to the MEKK1 N-terminal domain established that MEKK1 functions as a scaffold, not merely a kinase, physically recruiting its downstream target.","evidence":"In vitro peptide binding, co-immunoprecipitation in transfected cells","pmids":["9405400"],"confidence":"High","gaps":["Whether the scaffold function is separable from kinase activation in vivo was unclear","Stoichiometry of the MEKK1-JNK complex was not determined"]},{"year":1998,"claim":"Linking MEKK1–JNK signaling to p53 stabilization (by blocking MDM2 binding) and to NF-AT4 nuclear import suppression (via CKIα) expanded MEKK1's functional reach beyond MAPK cascades into transcription factor regulation and cell-fate decisions.","evidence":"In vivo ubiquitination assays, p53-MDM2 co-IP, NF-AT4 nuclear import assays","pmids":["9724739","9630228"],"confidence":"High","gaps":["Whether MEKK1 directly phosphorylates CKIα was not tested","The relative contribution of p53 stabilization vs. JNK-mediated phosphorylation to apoptosis was not dissected"]},{"year":1999,"claim":"MEKK1 knockout studies in ES cells and cardiomyocytes established stimulus-specific requirements: MEKK1 is essential for JNK activation by microtubule toxins and oxidative stress but dispensable for p38 activation, and protects cardiomyocytes from apoptosis by suppressing TNF-α.","evidence":"Targeted MEKK1 gene disruption in ES cells; JNK, p38 kinase assays; apoptosis and TNF-α measurement","pmids":["10212239","10611349"],"confidence":"High","gaps":["MEKK1's role in response to other stress stimuli (e.g., UV, osmotic) in KO cells was not systematically tested","Compensatory mechanisms by other MAP3Ks were not fully explored"]},{"year":1999,"claim":"Identifying α-actinin as a direct MEKK1-binding partner that tethers it to actin stress fibers and focal adhesions linked MEKK1 to cytoskeletal mechanotransduction, independent of its kinase activity.","evidence":"Yeast two-hybrid, in vitro binding with purified α-actinin, immunofluorescence co-localization with kinase-dead mutant","pmids":["10401575"],"confidence":"High","gaps":["Whether focal adhesion localization is required for anoikis signaling was not tested","The full set of cytoskeletal anchors for MEKK1 was not defined"]},{"year":2000,"claim":"Demonstrating that MEKK1's N-terminal domain binds ERK2, MEK1, and Raf-1 established it as a scaffold for the entire ERK module in addition to the JNK module, and linked MEKK1 to NF-κB activation via IKK-2 downstream of Raf.","evidence":"Co-immunoprecipitation of endogenous proteins; dominant-negative MEKK1 blocking NF-κB reporter","pmids":["10969079","10758165"],"confidence":"Medium","gaps":["Scaffold function for ERK was based on co-IP without in vitro reconstitution","Whether MEKK1 scaffolding of ERK and JNK modules is mutually exclusive was not tested"]},{"year":2001,"claim":"Discovering that the PHD/RING domain of MEKK1 is an E3 ubiquitin ligase for ERK1/2 revealed an unprecedented dual kinase–ligase mechanism by which MEKK1 simultaneously activates JNK and degrades ERK during stress, explaining pathway selectivity during apoptosis.","evidence":"In vitro E3 ligase reconstitution with ubiquitin, E1, E2; in vivo ubiquitination; ERK2 docking-motif mutants","pmids":["12049732"],"confidence":"High","gaps":["The identity of the E2 ubiquitin-conjugating enzyme was not determined","Structural basis for how kinase and ligase domains coordinate was unknown"]},{"year":2002,"claim":"Multiple studies in 2001–2002 defined the regulatory network controlling MEKK1: RIP phosphorylates Ser-957/994 to activate MEKK1 for TNF-α/NF-κB signaling; PAK1 phosphorylates Ser-67 to block JNK binding; and caspase-generated 91-kDa fragment relocalization (not downstream kinase activation) drives apoptosis.","evidence":"In vitro kinase assays with phospho-site mutants; co-IP in RIP-deficient Jurkat cells; membrane-targeting of 91-kDa fragment","pmids":["11369754","12228228","11782455"],"confidence":"High","gaps":["The phosphatase that dephosphorylates Ser-67 upon stress was not identified","Whether RIP-mediated activation and caspase cleavage are sequential or alternative was unclear"]},{"year":2002,"claim":"In vivo cardiac studies showed MEKK1 is required for pressure overload-induced JNK activation and Gαq-mediated cardiac hypertrophy, establishing a non-redundant physiological role in the heart.","evidence":"MEKK1 KO mice with aortic banding and Gαq transgenic cross; JNK activity, echocardiography, ANF expression","pmids":["12122119","11891332"],"confidence":"High","gaps":["Whether MEKK1 kinase or E3 ligase activity mediates the cardiac phenotype was not dissected","Downstream transcriptional targets in hypertrophy beyond ANF were not characterized"]},{"year":2003,"claim":"Identifying RhoA-GTP as a direct activator and Axin as a scaffold partner of MEKK1 connected it to cytoskeletal Rho signaling and the Wnt pathway, while demonstrating that MEKK1 drives uPA expression for cell migration/invasion revealed its role in tissue remodeling.","evidence":"In vitro binding/kinase assays with RhoA and PHD mutants; Axin co-IP in MEKK1−/− MEFs; uPA activity in KO fibroblasts with rescue","pmids":["14581471","12878610","12493778"],"confidence":"High","gaps":["Whether RhoA activates MEKK1 in the context of focal adhesions was not shown","The Axin–MEKK1 binding site on MEKK1 was not mapped"]},{"year":2006,"claim":"Extending the E3 ligase substrates to c-Jun and Fra-2 showed that MEKK1 remodels the AP-1 transcription factor repertoire: it ubiquitinates and degrades c-Jun and Fra-2, while suppressing JunB mRNA, thereby sculpting AP-1 composition to control uPA expression and apoptotic sensitivity.","evidence":"In vitro/in vivo ubiquitination of c-Jun; MEKK1−/− cells with elevated c-Jun/JunB; Fra-2 ubiquitination assay; AP-1 and uPA reporter","pmids":["17101801","15558021"],"confidence":"High","gaps":["Whether additional AP-1 family members are MEKK1 E3 substrates was not tested","The relative contribution of kinase vs. ligase activity to AP-1 remodeling was not fully separated"]},{"year":2006,"claim":"Identifying DJ-1 as a cytoplasmic sequestrator of MEKK1 that inhibits its kinase activity, with the Parkinson-associated L166P mutant losing this ability, linked MEKK1 regulation to neurodegeneration.","evidence":"Co-IP, in vitro kinase assay, subcellular fractionation, immunofluorescence with DJ-1 KD and L166P mutant","pmids":["18309325"],"confidence":"High","gaps":["Whether DJ-1 loss contributes to dopaminergic neuron death via MEKK1 in vivo was not tested","The DJ-1 binding site on MEKK1 was not mapped"]},{"year":2006,"claim":"In vivo metastasis studies confirmed that MEKK1 controls tumor cell dissemination through uPA and gelatinase regulation, establishing a physiological role for the MEKK1–uPA axis in cancer progression.","evidence":"MEKK1−/− × PyMT transgenic mice; lung metastasis quantification; uPA/gelatinase assays; siRNA in MDA-MB-231 cells","pmids":["16568086"],"confidence":"High","gaps":["Whether kinase or E3 ligase activity of MEKK1 drives the metastatic phenotype was not determined","Human tumor validation beyond siRNA in cell lines was limited"]},{"year":2007,"claim":"Compound mutant mouse studies showed MEKK1 preferentially phosphorylates JNK1 over JNK2 via MKK4 to control eyelid closure morphogenesis, demonstrating isoform selectivity in a developmental context.","evidence":"Mekk1/Jnk1/Jnk2 compound mutant mice; JNK isoform phosphorylation; c-Jun and PAI1 readouts","pmids":["18032450"],"confidence":"High","gaps":["Structural basis for JNK1 preference was not resolved","Whether MKK7 also contributes to eyelid closure was not addressed"]},{"year":2008,"claim":"Placing MEKK1 downstream of TRAF6/IPS-1 in the RIG-I/MDA5 innate antiviral pathway showed that MEKK1 is required for IFN-β induction, extending its role to innate immunity.","evidence":"TRAF6−/− and TAK1−/− MEFs; MEKK1 siRNA; MEKK1+IRF3 co-expression; IFN-β reporter","pmids":["18984593"],"confidence":"High","gaps":["Whether MEKK1 directly phosphorylates IRF3 or acts through an intermediate kinase was not determined","Redundancy with other MAP3Ks in antiviral signaling was incompletely explored"]},{"year":2010,"claim":"Patient mutation studies established that MAP3K1 gain-of-function mutations cause 46,XY disorders of sex development by enhancing RHOA/MAP3K4/FRAT1 binding and reducing RAC1 binding, shifting signaling toward WNT/β-catenin/FOXL2 and away from SOX9/FGF9, while Axin-MEKK1 interaction was shown to require E3 ligase (not kinase) activity for Wnt-driven transcription.","evidence":"Linkage analysis and sequencing in DSD families; phospho-p38/ERK assays; co-IP for RHOA/RAC1/MAP3K4/FRAT1; Axin co-IP with ligase/kinase mutants; TCF/LEF reporter","pmids":["21129722","24135036","20128690"],"confidence":"High","gaps":["Whether mutations affect MEKK1 E3 ligase activity specifically was not tested","The mechanism by which altered RHOA binding shifts downstream pathway selection was not fully resolved"]},{"year":2011,"claim":"MAP3K1 deficiency causes JNK-independent retinal defects including Müller glia overproduction through cyclin D1/CDK4/6-RB-E2F dysregulation, revealing a kinase-cascade-independent developmental role.","evidence":"Map3k1 KO mice; BrdU, TUNEL, cell-type immunostaining; compound mutants with Jnk1−/− and Jnk1/2 hemizygotes","pmids":["21862560"],"confidence":"High","gaps":["Whether the E3 ligase activity mediates the retinal phenotype was not tested","Direct substrates controlling cyclin D1 were not identified"]},{"year":2018,"claim":"CRISPR knockout of MAP3K1 in PIK3CA-mutant breast cancer cells revealed that MAP3K1 normally promotes IRS-1 degradation via JNK signaling; its loss stabilizes IRS-1 and enhances PI3Kα/AKT signaling, explaining the frequent co-occurrence of MAP3K1 and PIK3CA mutations in breast cancer.","evidence":"CRISPR KO; phospho-AKT/IRS-1 immunoblotting; IRS-1/p85 co-IP; 3D acinar growth; xenograft studies","pmids":["29765551"],"confidence":"High","gaps":["Whether MEKK1 E3 ligase activity directly ubiquitinates IRS-1 was not tested","Clinical validation of combined PI3Kα inhibitor sensitivity in MAP3K1-mutant tumors was not provided"]},{"year":null,"claim":"Key unresolved questions include the structural basis for how the kinase and E3 ligase domains of MEKK1 are coordinately regulated, the identity of the E2 enzyme(s) for its ubiquitin ligase activity, and the mechanism by which DSD-associated mutations alter the balance between RHOA and RAC1 binding at the structural level.","evidence":"","pmids":[],"confidence":"Low","gaps":["No crystal or cryo-EM structure of full-length MEKK1 or its PHD/RING domain in complex with substrates","E2 ubiquitin-conjugating enzyme identity unknown","Structural mechanism of DSD mutation-induced binding partner switching unresolved"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,3,16,17,18]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,3,35]},{"term_id":"GO:0016874","term_label":"ligase activity","supporting_discovery_ids":[12,23,26,31]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,10,36]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[5,6,12]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[8]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,13]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,2,7,9,14,15,18,30]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[1,4,5,13,23]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[29]},{"term_id":"R-HSA-392499","term_label":"Metabolism of proteins","supporting_discovery_ids":[12,23,26]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[27,30,32,34]}],"complexes":[],"partners":["MKK4","JNK1","ERK2","RHOA","AXIN1","RIPK1","ACTN1","DJ-1"],"other_free_text":[]},"mechanistic_narrative":"MAP3K1 (MEKK1) is a multifunctional serine/threonine kinase and E3 ubiquitin ligase that integrates stress, cytokine, and developmental signals by acting as both a catalytic activator and a scaffold for multiple MAPK cascades. Its kinase domain phosphorylates and activates SEK1/MKK4 and MKK7 to drive JNK/SAPK signaling, and MEK1 to activate ERK1/2, while its PHD/RING finger domain functions as an E3 ubiquitin ligase that ubiquitinates ERK1/2, c-Jun, and Fra-2 for proteasomal degradation, and promotes Wnt/β-catenin-dependent transcription through interaction with Axin [PMID:7997270, PMID:12049732, PMID:17101801, PMID:20128690]. MAP3K1 is activated by caspase-3 cleavage at Asp-68, which releases a 91-kDa kinase fragment that relocalizes from a particulate compartment to the cytosol to drive apoptosis, by RIP-mediated phosphorylation at Ser-957/994 downstream of TNF-α, and by RhoA-GTP binding to its N-terminal/PHD region; it is negatively regulated by PAK1 phosphorylation at Ser-67, DJ-1-mediated cytoplasmic sequestration, and STK38 binding [PMID:9576928, PMID:11782455, PMID:11369754, PMID:14581471, PMID:12228228, PMID:18309325]. Gain-of-function mutations in MAP3K1 cause 46,XY disorders of sex development by shifting MAPK signaling toward WNT/β-catenin/FOXL2 at the expense of SOX9/FGF9 through altered binding of RHOA, MAP3K4, RAC1, and FRAT1 [PMID:21129722, PMID:24135036]."},"prefetch_data":{"uniprot":{"accession":"Q13233","full_name":"Mitogen-activated protein kinase kinase kinase 1","aliases":["MAPK/ERK kinase kinase 1","MEK kinase 1","MEKK 1"],"length_aa":1512,"mass_kda":164.5,"function":"Component of a protein kinase signal transduction cascade (PubMed:9808624). Activates the ERK and JNK kinase pathways by phosphorylation of MAP2K1 and MAP2K4 (PubMed:9808624). May phosphorylate the MAPK8/JNK1 kinase (PubMed:17761173). Activates CHUK and IKBKB, the central protein kinases of the NF-kappa-B pathway (PubMed:9808624)","subcellular_location":"","url":"https://www.uniprot.org/uniprotkb/Q13233/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MAP3K1","classification":"Not Classified","n_dependent_lines":16,"n_total_lines":1208,"dependency_fraction":0.013245033112582781},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/MAP3K1","total_profiled":1310},"omim":[{"mim_id":"618068","title":"SPERMATOGENIC LEUCINE ZIPPER PROTEIN 1; SPZ1","url":"https://www.omim.org/entry/618068"},{"mim_id":"616786","title":"MITOGEN-ACTIVATED PROTEIN KINASE-BINDING PROTEIN 1; MAPKBP1","url":"https://www.omim.org/entry/616786"},{"mim_id":"616711","title":"TAO KINASE 3; TAOK3","url":"https://www.omim.org/entry/616711"},{"mim_id":"615814","title":"SERINE/THREONINE/TYROSINE-INTERACTING PROTEIN; STYX","url":"https://www.omim.org/entry/615814"},{"mim_id":"614899","title":"DEAFNESS, AUTOSOMAL RECESSIVE 93; DFNB93","url":"https://www.omim.org/entry/614899"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MAP3K1"},"hgnc":{"alias_symbol":["MEKK","MAPKKK1"],"prev_symbol":["MEKK1"]},"alphafold":{"accession":"Q13233","domains":[{"cath_id":"-","chopping":"303-399_439-483","consensus_level":"medium","plddt":80.1885,"start":303,"end":483},{"cath_id":"1.25.10","chopping":"543-599_628-744","consensus_level":"medium","plddt":88.3175,"start":543,"end":744},{"cath_id":"-","chopping":"746-872","consensus_level":"medium","plddt":85.3879,"start":746,"end":872},{"cath_id":"3.30.200.20","chopping":"1212-1326","consensus_level":"medium","plddt":78.3103,"start":1212,"end":1326},{"cath_id":"1.10.510.10","chopping":"1330-1512","consensus_level":"medium","plddt":88.6962,"start":1330,"end":1512}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13233","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13233-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13233-F1-predicted_aligned_error_v6.png","plddt_mean":58.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MAP3K1","jax_strain_url":"https://www.jax.org/strain/search?query=MAP3K1"},"sequence":{"accession":"Q13233","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13233.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13233/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13233"}},"corpus_meta":[{"pmid":"7997270","id":"PMC_7997270","title":"Activation 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SAPK/JNK stress-activated protein kinases, defining MEKK1 as a MAP3K in the JNK signaling cascade.\",\n      \"method\": \"In vitro kinase assay; expression in COS-7 cells and NIH3T3 inducible cell lines\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution of kinase cascade, replicated across multiple cell systems, >700 citations\",\n      \"pmids\": [\"7997270\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"MEKK1 is cleaved by caspase 3 (CPP32) after residue D68 in response to Fas ligation; this cleavage is required for MEKK1 kinase activation and redistributes MEKK1 from a Triton-insoluble (particulate) compartment to a Triton-soluble (diffuse cytoplasmic) compartment.\",\n      \"method\": \"Sequencing of proteolytic cleavage products; in vitro and in vivo caspase cleavage assays; immunofluorescence; subcellular fractionation; viral and chemical caspase inhibitors\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct identification of cleavage site by sequencing, in vivo and in vitro validation, multiple orthogonal methods\",\n      \"pmids\": [\"9576928\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"MEKK1 binds directly to the N-terminal non-catalytic domain of JNK/SAPK in vitro and in transfected cells; this interaction facilitates JNK activation by MEKK1.\",\n      \"method\": \"In vitro binding with immobilized MEKK1-derived peptides; co-immunoprecipitation in transfected cells; selective extraction from cell lysates\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct in vitro binding confirmed by reciprocal co-IP and peptide pulldown\",\n      \"pmids\": [\"9405400\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"MEKK1 autophosphorylates on Thr-575 within its activation loop (between kinase subdomains VII and VIII), and this autophosphorylation is required for full kinase activity; mutation of Thr-587 to alanine eliminates substrate (MEK/SEK) phosphorylation but not autophosphorylation.\",\n      \"method\": \"Site-directed mutagenesis; in vitro kinase assay; phosphatase treatment; metabolic labeling\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro kinase assays with mutagenesis, identified specific autophosphorylation sites\",\n      \"pmids\": [\"9078260\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1997,\n      \"finding\": \"Caspase cleavage of MEKK1 is required for its activation during anoikis; the MEKK1 cleavage product stimulates apoptosis, and a cleavage-resistant MEKK1 mutant partially protects cells from anoikis, establishing a caspase–MEKK1 positive feedback loop.\",\n      \"method\": \"Overexpression of MEKK1 cleavage product and cleavage-resistant mutant; caspase activity assays; anoikis functional assays\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — mutant rescue and loss-of-function in defined cellular apoptosis model, >460 citations\",\n      \"pmids\": [\"9244305\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"MEKK1 activates the MEKK1-JNK signaling axis to stabilize p53 by reducing its ubiquitination; JNK phosphorylates p53, which abolishes MDM2 binding and prevents p53 ubiquitination, leading to increased p53 transcriptional activity and apoptosis.\",\n      \"method\": \"Expression of constitutively active ΔMEKK1; in vivo ubiquitination assay; in vitro phosphorylation of p53 by immunopurified JNK; co-immunoprecipitation of p53-MDM2; luciferase reporter assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal biochemical methods in a single study\",\n      \"pmids\": [\"9724739\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"MEKK1 suppresses NF-AT4 nuclear import by stabilizing the interaction between NF-AT4 and casein kinase Iα (CKIα), which phosphorylates NF-AT4 and causes intramolecular masking of its nuclear localization signal.\",\n      \"method\": \"Identification of CKIα as NF-AT4 binding partner; co-immunoprecipitation; nuclear import assays; phosphorylation assays\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP and functional nuclear import assay, >260 citations\",\n      \"pmids\": [\"9630228\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"MEKK1 is required for JNK activation in response to microtubule toxins (taxol) but not actin fiber disruption; MEKK1-deficient embryonic stem cells fail to activate JNK and show increased apoptosis in response to taxol, while MEKK2 disruption has no effect.\",\n      \"method\": \"Targeted gene disruption (MEKK1-/- ES cells); JNK kinase assay; apoptosis assay; cell cycle analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with specific pathway readout, genetic specificity confirmed by MEKK2 KO comparison\",\n      \"pmids\": [\"10212239\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"MEKK1 interacts with the actin-crosslinking protein α-actinin via residues 221–559 in its N-terminal domain, and both endogenous and overexpressed MEKK1 co-localize with α-actinin along actin stress fibers and at focal adhesions; kinase activity is not required for this localization.\",\n      \"method\": \"Yeast two-hybrid screen; co-immunoprecipitation; in vitro binding with purified α-actinin; immunofluorescence co-localization; kinase-inactive mutant\",\n      \"journal\": \"Cell motility and the cytoskeleton\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct in vitro binding confirmed, subcellular localization validated by immunofluorescence with kinase-dead mutant\",\n      \"pmids\": [\"10401575\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"MEKK1 deficiency in embryonic stem cell-derived cardiac myocytes abolishes JNK activation but not p38 activation in response to oxidative stress (H2O2); the MEKK1-JNK pathway protects against apoptosis by suppressing TNF-α production.\",\n      \"method\": \"Targeted MEKK1 gene disruption in ES cells; JNK and p38 kinase assays; TNF-α measurement; apoptosis assay\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — clean KO with multiple pathway readouts and defined cytokine mechanism\",\n      \"pmids\": [\"10611349\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"MEKK1 binds directly to ERK2, MEK1, and Raf-1 via its N-terminal regulatory domain, demonstrating that MEKK1 can scaffold the entire ERK MAP kinase module.\",\n      \"method\": \"Co-immunoprecipitation of endogenous proteins\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP of endogenous proteins but single-lab, single method\",\n      \"pmids\": [\"10969079\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"Raf-mediated NF-κB activation requires MEKK1 as a membrane shuttle kinase; a dominant-negative MEKK1 blocks Raf- and PMA-induced NF-κB activation, which depends on IKK-2 but not the classical MEK-ERK cascade.\",\n      \"method\": \"Dominant-negative MEKK1 expression; NF-κB reporter assay; IKK activity assay; pharmacological inhibitors\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — dominant-negative plus pathway-specific inhibitors, single lab\",\n      \"pmids\": [\"10758165\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"The PHD/RING finger-like domain of MEKK1 functions as an E3 ubiquitin ligase that ubiquitinates ERK1/2, promoting their proteasome-dependent degradation during stress; both MEKK1 kinase activity and a docking motif on ERK1/2 are required for ERK ubiquitination.\",\n      \"method\": \"In vitro ubiquitin ligase assay; in vivo ubiquitination; docking motif mutations on ERK2; apoptosis assay in ERK2 docking mutant cells\",\n      \"journal\": \"Molecular cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro reconstitution of E3 ligase activity with mutagenesis and in vivo validation, >260 citations\",\n      \"pmids\": [\"12049732\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Caspase-generated 91-kDa MEKK1 kinase fragment relocalizes from a particulate fraction to a soluble cytoplasmic fraction; this relocalization (not JNK, ERK, NF-κB, or p300 activation) is necessary for MEKK1's pro-apoptotic function.\",\n      \"method\": \"Subcellular fractionation; membrane-targeting signal added to 91-kDa fragment; caspase activation assays; kinase activity assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct manipulation of localization with functional consequence, multiple orthogonal readouts\",\n      \"pmids\": [\"11782455\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"MEKK1 mediates pressure overload-induced JNK activation in the heart; MEKK1-deficient mice show loss of JNK activation after aortic banding while cardiac hypertrophy still occurs, indicating MEKK1 is required for JNK activation but not hypertrophy. MEKK1 protects against apoptosis and inflammation under pressure overload.\",\n      \"method\": \"MEKK1 knockout mice; aortic banding model; JNK activity assay; cardiac morphometry; apoptosis assay\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo KO with defined pathway readout, multiple physiological endpoints\",\n      \"pmids\": [\"12122119\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"MEKK1 is essential for Gαq-induced cardiac hypertrophy; MEKK1 knockout abolishes JNK activation, cardiac mass increase, myocyte hypertrophy, and ANF induction by Gαq, while improving ventricular function.\",\n      \"method\": \"MEKK1 knockout ES cell-derived cardiac myocytes; Gαq-overexpressing transgenic mice crossed with MEKK1-/- mice; JNK kinase assay; echocardiography; ANF expression\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vitro and in vivo KO with multiple specific pathway and phenotypic readouts\",\n      \"pmids\": [\"11891332\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Receptor-interacting protein (RIP) physically associates with and phosphorylates MEKK1 at Ser-957 and Ser-994, thereby activating MEKK1; this RIP-MEKK1 interaction mediates TNF-α-induced IKKβ/NF-κB activation.\",\n      \"method\": \"In vitro binding; co-immunoprecipitation; in vitro kinase assay (RIP phosphorylation of MEKK1); phosphorylation-site mutants; RIP-deficient Jurkat cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay identifying specific phosphorylation sites with mutagenesis and KO cell validation\",\n      \"pmids\": [\"11369754\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PAK1 phosphorylates MEKK1 on Ser-67 within a D domain that mediates JNK/SAPK binding; constitutive Ser-67 phosphorylation in resting cells inhibits JNK binding to MEKK1, and stress stimuli cause dephosphorylation of Ser-67 to allow JNK binding.\",\n      \"method\": \"In vitro kinase assay (PAK1 phosphorylation of MEKK1 N-terminus); phosphorylation-site mutants; co-immunoprecipitation; phospho-specific analysis in stressed cells\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — identification of specific phosphorylation site by kinase assay with mutagenesis and in-cell validation\",\n      \"pmids\": [\"12228228\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"RhoA (but not Rac or Cdc42) binds to the N-terminal one-third of MEKK1 including its PHD domain; RhoA-GTP stimulates MEKK1 kinase activity up to 10-fold toward MEK4, and mutation of the essential PHD cysteine prevents RhoA interaction.\",\n      \"method\": \"In vitro binding assay; co-immunoprecipitation; in vitro kinase assay; PHD domain mutagenesis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct in vitro binding and kinase stimulation with mutagenesis\",\n      \"pmids\": [\"14581471\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MEKK1 is required for inducible urokinase-type plasminogen activator (uPA) expression; MEKK1-deficient fibroblasts show greatly reduced uPA expression/activity in response to PMA or FGF-2, dependent on MEKK1-driven MKK1 and JNK activity; MEKK2 disruption has no effect.\",\n      \"method\": \"MEKK1 knockout fibroblasts; rescue by MEKK1 transfection; uPA activity assay; genetic specificity via MEKK2 disruption\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with rescue, genetic specificity confirmed by MEKK2 comparison\",\n      \"pmids\": [\"12493778\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MEKK1 activity drives formation of polyglutamine-containing inclusion bodies by recruiting polyQ-containing huntingtin fragments into a particulate/insoluble fraction; kinase-dead MEKK1 cannot stimulate inclusion body formation.\",\n      \"method\": \"Overexpression of active vs. kinase-dead MEKK1; cellular fractionation; fluorescence microscopy of huntingtin-GFP inclusion bodies\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — kinase-dead mutant comparison with fractionation, single lab\",\n      \"pmids\": [\"11352944\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Ceramide directly binds MEKK1 (but not c-Raf) in glomerular endothelial cells, as demonstrated by photoaffinity labeling and ceramide-sepharose affinity chromatography, leading to SAPK/JNK cascade activation.\",\n      \"method\": \"Radioiodinated photoaffinity ceramide analogue labeling; ceramide-sepharose affinity chromatography; JNK/SEK phosphorylation assays\",\n      \"journal\": \"Biochimica et biophysica acta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct binding demonstrated by two independent methods (photoaffinity + affinity chromatography), single lab\",\n      \"pmids\": [\"15164763\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Glutathione S-transferase Mu 1-1 (GST M1-1) directly binds MEKK1, inhibits its kinase activity in a catalysis-independent manner, and interferes with MEKK1-SEK1 interaction, thereby suppressing MEKK1-induced apoptosis.\",\n      \"method\": \"In vitro binding assay; in vitro kinase assay; co-immunoprecipitation of endogenous proteins; binding competition assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vitro binding and kinase assays with co-IP of endogenous proteins, single lab\",\n      \"pmids\": [\"15299005\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The PHD/RING finger domain of MEKK1 acts as an E3 ubiquitin ligase toward c-Jun in response to osmotic stress; MEKK1 ubiquitinates and degrades c-Jun in vitro and in vivo, and MEKK1-/- cells have elevated c-Jun levels. c-Jun downregulation by MEKK1 promotes apoptosis.\",\n      \"method\": \"In vitro ubiquitin ligase assay; in vivo ubiquitination; MEKK1-/- cells; apoptosis assay with c-Jun overexpression\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro E3 ligase reconstitution confirmed in vivo with KO cells\",\n      \"pmids\": [\"17101801\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MEKK1 controls tumor cell dissemination and lung metastasis in PyMT mammary cancer by regulating urokinase-type plasminogen activator (uPA) expression, gelatinase activity, and basement membrane integrity; MEKK1-/- tumors show markedly reduced uPA, reduced cell migration and invasion.\",\n      \"method\": \"MEKK1-/- mice crossed with PyMT transgenic; in vivo metastasis assay; uPA expression and activity; gelatinase zymography; siRNA knockdown in MDA-MB-231 cells; invasion assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — in vivo KO plus siRNA knockdown with multiple mechanistic readouts\",\n      \"pmids\": [\"16568086\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"DJ-1 directly binds and inhibits MEKK1 kinase activity through its C-terminus, sequesters MEKK1 in the cytoplasm; the pathogenic DJ-1 L166P mutant cannot associate with MEKK1 and allows MEKK1 nuclear translocation, sensitizing cells to UV-induced MEKK1-SEK1-JNK1-mediated cell death.\",\n      \"method\": \"Co-immunoprecipitation; in vitro kinase assay; subcellular fractionation; immunofluorescence; DJ-1 knockdown; L166P mutant analysis\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — direct binding, kinase inhibition, and localization with pathogenic mutant validation\",\n      \"pmids\": [\"18309325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MEKK1 regulates the AP-1 transcription factor repertoire by suppressing JunB mRNA expression and by inducing Fra-2 ubiquitination and degradation; loss of MEKK1 results in elevated JunB that forms an inhibitory AP-1 complex suppressing uPA transcription.\",\n      \"method\": \"MEKK1-/- cells; RT-PCR for JunB mRNA; Fra-2 ubiquitination assay; AP-1 reporter assay; uPA promoter analysis\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — KO phenotype combined with ubiquitination assay and reporter readout, single lab\",\n      \"pmids\": [\"15558021\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"MEKK1 mediates eyelid closure morphogenesis through differential phosphorylation of JNK1 and JNK2; JNK1 (possessing unique Gly177 and Ser179 residues) is phosphorylated more efficiently than JNK2 by the MEKK1-MKK4 pathway activated by activin B, controlling downstream c-Jun phosphorylation and PAI1 expression.\",\n      \"method\": \"Mekk1/Jnk1/Jnk2 compound mutant mice; JNK phosphorylation assays; c-Jun phosphorylation; PAI1 expression; eyelid closure phenotype scoring\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic epistasis with compound mutants plus biochemical pathway analysis\",\n      \"pmids\": [\"18032450\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"STK38 (NDR kinase) physically interacts with the catalytic domain of MEKK1 and negatively regulates MEKK1 activity by converting it from its phosphorylated to non-phosphorylated form, suppressing MEKK1 autophosphorylation and downstream signaling.\",\n      \"method\": \"Co-immunoprecipitation; in vitro kinase assay; shRNA knockdown of STK38; autophosphorylation assay\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — direct interaction with kinase assay and RNAi validation, single lab\",\n      \"pmids\": [\"17906693\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"TRAF6 and MEKK1 act downstream of IPS-1 in the RIG-I/MDA5 antiviral pathway; MEKK1 (but not TAK1) is required for IFN-β induction in response to poly(I:C) and VSV, and co-expression of MEKK1 with IRF3 is sufficient to induce IFN-β.\",\n      \"method\": \"TRAF6-/- and TAK1-/- MEFs; siRNA knockdown of MEKK1; overexpression of MEKK1+IRF3; NF-κB, JNK, p38 activation assays; IFN-β reporter assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO and KD with overexpression rescue and defined pathway placement\",\n      \"pmids\": [\"18984593\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Mutations in MAP3K1 causing 46,XY disorders of sex development (DSD) alter phosphorylation of downstream targets p38 and ERK1/2, and enhance binding of RHOA to the MAP3K1 complex in patient-derived lymphoblastoid cells, implicating MAP3K1 in testis determination via MAPK signaling.\",\n      \"method\": \"Linkage analysis; sequencing of patient samples; phospho-p38 and phospho-ERK1/2 assays in patient lymphoblastoid cells; co-immunoprecipitation for RHOA binding\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — patient mutations validated by functional biochemistry in primary cells, multiple families\",\n      \"pmids\": [\"21129722\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MAP3K1 functionally interacts with Axin1; this interaction is induced by Wnt stimulation; MAP3K1's E3 ubiquitin ligase activity (but not kinase activity) is required for TCF/LEF-driven transcription and Wnt target gene expression.\",\n      \"method\": \"Immunoprecipitation-coupled proteomics; co-immunoprecipitation with Wnt stimulation; siRNA knockdown; ubiquitin ligase mutant and kinase mutant expression; TCF/LEF luciferase reporter assay\",\n      \"journal\": \"Biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — proteomics-identified interaction validated biochemically with domain-specific mutants separating kinase from E3 ligase function\",\n      \"pmids\": [\"20128690\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MAP3K1 mutations causing 46,XY DSD enhance binding of RHOA, MAP3K4, and FRAT1 while reducing RAC1 binding; these mutations tilt signaling toward WNT/β-catenin/FOXL2 and away from SOX9/FGF9 pathways; overexpressing RHOA or reducing MAP3K4 phenocopies the mutations.\",\n      \"method\": \"Transfection of wild-type and mutant MAP3K1 in NT2/D1 cells; co-immunoprecipitation; phosphorylation assays; siRNA knockdown of RHOA/MAP3K4; reporter assays for WNT/β-catenin and SOX9/FGF9\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods; gain-of-function, phenocopy and anti-phenocopy experiments\",\n      \"pmids\": [\"24135036\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"MEKK1 activation by IL-1β mediates canonical NF-κB pathway activation, which is required for IL-1β-induced increase in intestinal tight junction permeability; MEKK1 also plays an essential role in MLCK gene activation downstream of IL-1β.\",\n      \"method\": \"siRNA knockdown of MEKK1 and NIK in Caco-2 monolayers; transepithelial resistance measurement; NF-κB pathway activation assays; MLCK promoter assay\",\n      \"journal\": \"The American journal of pathology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — siRNA knockdown with functional barrier assay and pathway readouts, single lab\",\n      \"pmids\": [\"21048223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MAP3K1 deficiency leads to increased proliferation, apoptosis, and Müller glial overproduction in developing retinas; this retinal defect is independent of the eye-open-at-birth phenotype and of JNK, but involves cyclin D1/CDK4/6-RB-E2F signaling.\",\n      \"method\": \"Map3k1 knockout mice; BrdU incorporation; TUNEL apoptosis assay; immunostaining for cell-type markers; compound mutant analysis with Jnk1-/- and Jnk1/2 hemizygotes; tarsorrhaphy control\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — KO with epistasis analysis using compound mutants and surgical controls\",\n      \"pmids\": [\"21862560\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"MEKK1 controls neurite regrowth after injury by simultaneously activating both ERK1/2 (via MEK1) and JNK2 (via MKK7); MEK1 and MKK7 compete for binding to MEKK1, creating a pathway cross-talk. RNAi knockdown of MEKK1 abolishes both ERK and JNK phosphorylation.\",\n      \"method\": \"RNAi knockdown; co-immunoprecipitation of MEK1 and MKK7 with MEKK1; ERK/JNK phosphorylation assays; neurite regrowth assay in PC12 cells\",\n      \"journal\": \"Molecular and cellular neurosciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — RNAi with co-IP of competing substrates, single lab\",\n      \"pmids\": [\"16006144\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Axin binds MEKK1 to activate JNK; Axin also binds MEKK4 at a distinct domain, and MEKK4 can mediate Axin-induced JNK activation in MEKK1-/- cells; MEKK1 and MEKK4 compete for Axin binding.\",\n      \"method\": \"Co-immunoprecipitation; MEKK1-/- MEFs; siRNA against MEKK4; JNK activation assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KO cells with siRNA epistasis and co-IP, single lab\",\n      \"pmids\": [\"12878610\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"p115 Rho GTPase-activating protein (p115 RhoGAP) binds to the N-terminal regulatory domain of MEKK1 via the RhoGAP SH3 domain; this interaction reduces MEKK1-induced AP-1 signaling, linking MEKK1 to cytoskeletal Rho regulation.\",\n      \"method\": \"Yeast two-hybrid screen; in vitro binding; co-immunoprecipitation; AP-1 reporter assay; SH3 deletion mutant\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — yeast two-hybrid confirmed by in vitro and co-IP binding with functional reporter assay\",\n      \"pmids\": [\"12115726\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Dietary isothiocyanates (ITCs) directly and covalently modify a specific cysteine residue in the ATP binding pocket of MEKK1, irreversibly inhibiting its kinase activity; this correlates with specific inhibition of SAPK/JNK but not parallel MAPK pathways.\",\n      \"method\": \"In vitro kinase assay; affinity reagent for ITC modification; cysteine-mutant MEKK1; kinase assay of endogenous immunopurified MEKK1; phospho-specific immunoblotting\",\n      \"journal\": \"BMC cancer\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — direct covalent modification identified with specific residue, in vitro and in vivo confirmed\",\n      \"pmids\": [\"17894894\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"MAP3K1 deficiency in PIK3CA-mutant breast cancer cells enhances AKT phosphorylation and downstream signaling by impairing MAP3K1-JNK signaling that normally promotes IRS-1 degradation; MAP3K1 loss increases IRS-1 stability and IRS-1/p85 binding, enhancing PI3Kα activity.\",\n      \"method\": \"CRISPR knockout of MAP3K1; phospho-AKT/IRS-1 immunoblotting; co-immunoprecipitation of IRS-1/p85; 3D acinar growth assay; in vivo xenograft efficacy studies\",\n      \"journal\": \"Oncotarget\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR KO with multiple mechanistic readouts, in vitro and in vivo validation\",\n      \"pmids\": [\"29765551\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MAP3K1 mutations causing 46,XY DSD cluster in three structural domains: an N-terminal GEF-homology domain (Met164–Glu231), PHD domain (Met442–Trp495), and ARMadillo repeat domain (Met566–Glu862); mutations differentially increase binding of RHOA, MAP3K4, and FRAT1 and decrease RAC1 binding depending on domain location.\",\n      \"method\": \"Structural modeling; co-immunoprecipitation for binding partners; downstream phosphorylation assays; patient mutation functional analysis\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 — co-IP binding studies with structural modeling, mechanistic follow-up on domain-specific mutations\",\n      \"pmids\": [\"30608580\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MAP3K1 (MEKK1) is a dual-function MAP3K that activates the JNK/SAPK pathway by phosphorylating SEK1/MKK4 (and MKK7), activates ERK1/2 via MEK1, and regulates NF-κB; it scaffolds these cascades through its large N-terminal domain that binds JNK, ERK2, MEK1, Raf-1, α-actinin, RhoA, and Axin, while its PHD/RING finger domain acts as an E3 ubiquitin ligase toward ERK1/2, c-Jun, and Fra-2; it is activated by caspase-3/7 cleavage (releasing an active 91-kDa fragment that redistributes to the cytosol to drive apoptosis), by RIP-mediated phosphorylation at Ser-957/994 downstream of TNF-α, and by autophosphorylation at Thr-575; it is negatively regulated by PAK1 phosphorylation of Ser-67, by GST M1-1 and STK38 binding, and by DJ-1-mediated cytoplasmic sequestration; in sex determination, gain-of-function mutations shift signaling toward WNT/β-catenin/FOXL2 at the expense of SOX9/FGF9 by altering RHOA, MAP3K4, and RAC1 binding, causing 46,XY gonadal dysgenesis.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MAP3K1 (MEKK1) is a multifunctional serine/threonine kinase and E3 ubiquitin ligase that integrates stress, cytokine, and developmental signals by acting as both a catalytic activator and a scaffold for multiple MAPK cascades. Its kinase domain phosphorylates and activates SEK1/MKK4 and MKK7 to drive JNK/SAPK signaling, and MEK1 to activate ERK1/2, while its PHD/RING finger domain functions as an E3 ubiquitin ligase that ubiquitinates ERK1/2, c-Jun, and Fra-2 for proteasomal degradation, and promotes Wnt/β-catenin-dependent transcription through interaction with Axin [PMID:7997270, PMID:12049732, PMID:17101801, PMID:20128690]. MAP3K1 is activated by caspase-3 cleavage at Asp-68, which releases a 91-kDa kinase fragment that relocalizes from a particulate compartment to the cytosol to drive apoptosis, by RIP-mediated phosphorylation at Ser-957/994 downstream of TNF-α, and by RhoA-GTP binding to its N-terminal/PHD region; it is negatively regulated by PAK1 phosphorylation at Ser-67, DJ-1-mediated cytoplasmic sequestration, and STK38 binding [PMID:9576928, PMID:11782455, PMID:11369754, PMID:14581471, PMID:12228228, PMID:18309325]. Gain-of-function mutations in MAP3K1 cause 46,XY disorders of sex development by shifting MAPK signaling toward WNT/β-catenin/FOXL2 at the expense of SOX9/FGF9 through altered binding of RHOA, MAP3K4, RAC1, and FRAT1 [PMID:21129722, PMID:24135036].\",\n  \"teleology\": [\n    {\n      \"year\": 1994,\n      \"claim\": \"Establishing MAP3K1 as a MAP3K in the JNK cascade resolved the identity of the kinase upstream of SEK1/MKK4 in stress signaling, placing MEKK1 at the apex of a three-tiered kinase module.\",\n      \"evidence\": \"In vitro kinase assay and COS-7/NIH3T3 expression showing MEKK1 phosphorylates SEK1 which activates SAPK/JNK\",\n      \"pmids\": [\"7997270\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MEKK1 also phosphorylates other MKKs (e.g., MKK7, MEK1) was not addressed\", \"Physiological stimuli activating MEKK1 were unknown\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Identifying caspase-3 cleavage at Asp-68 and autophosphorylation at Thr-575 revealed two distinct activation mechanisms — proteolytic release of an active kinase fragment during apoptosis and autophosphorylation-dependent catalytic competence — establishing how MEKK1 integrates apoptotic and stress signals.\",\n      \"evidence\": \"Sequencing of cleavage products, in vitro/in vivo caspase assays, subcellular fractionation, site-directed mutagenesis of autophosphorylation sites\",\n      \"pmids\": [\"9576928\", \"9078260\", \"9244305\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other caspases (e.g., caspase-7) also cleave MEKK1 was not fully defined\", \"The phosphatase reversing Thr-575 autophosphorylation was not identified\"]\n    },\n    {\n      \"year\": 1997,\n      \"claim\": \"Demonstrating direct JNK binding to the MEKK1 N-terminal domain established that MEKK1 functions as a scaffold, not merely a kinase, physically recruiting its downstream target.\",\n      \"evidence\": \"In vitro peptide binding, co-immunoprecipitation in transfected cells\",\n      \"pmids\": [\"9405400\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the scaffold function is separable from kinase activation in vivo was unclear\", \"Stoichiometry of the MEKK1-JNK complex was not determined\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Linking MEKK1–JNK signaling to p53 stabilization (by blocking MDM2 binding) and to NF-AT4 nuclear import suppression (via CKIα) expanded MEKK1's functional reach beyond MAPK cascades into transcription factor regulation and cell-fate decisions.\",\n      \"evidence\": \"In vivo ubiquitination assays, p53-MDM2 co-IP, NF-AT4 nuclear import assays\",\n      \"pmids\": [\"9724739\", \"9630228\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MEKK1 directly phosphorylates CKIα was not tested\", \"The relative contribution of p53 stabilization vs. JNK-mediated phosphorylation to apoptosis was not dissected\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"MEKK1 knockout studies in ES cells and cardiomyocytes established stimulus-specific requirements: MEKK1 is essential for JNK activation by microtubule toxins and oxidative stress but dispensable for p38 activation, and protects cardiomyocytes from apoptosis by suppressing TNF-α.\",\n      \"evidence\": \"Targeted MEKK1 gene disruption in ES cells; JNK, p38 kinase assays; apoptosis and TNF-α measurement\",\n      \"pmids\": [\"10212239\", \"10611349\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"MEKK1's role in response to other stress stimuli (e.g., UV, osmotic) in KO cells was not systematically tested\", \"Compensatory mechanisms by other MAP3Ks were not fully explored\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Identifying α-actinin as a direct MEKK1-binding partner that tethers it to actin stress fibers and focal adhesions linked MEKK1 to cytoskeletal mechanotransduction, independent of its kinase activity.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding with purified α-actinin, immunofluorescence co-localization with kinase-dead mutant\",\n      \"pmids\": [\"10401575\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether focal adhesion localization is required for anoikis signaling was not tested\", \"The full set of cytoskeletal anchors for MEKK1 was not defined\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstrating that MEKK1's N-terminal domain binds ERK2, MEK1, and Raf-1 established it as a scaffold for the entire ERK module in addition to the JNK module, and linked MEKK1 to NF-κB activation via IKK-2 downstream of Raf.\",\n      \"evidence\": \"Co-immunoprecipitation of endogenous proteins; dominant-negative MEKK1 blocking NF-κB reporter\",\n      \"pmids\": [\"10969079\", \"10758165\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Scaffold function for ERK was based on co-IP without in vitro reconstitution\", \"Whether MEKK1 scaffolding of ERK and JNK modules is mutually exclusive was not tested\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Discovering that the PHD/RING domain of MEKK1 is an E3 ubiquitin ligase for ERK1/2 revealed an unprecedented dual kinase–ligase mechanism by which MEKK1 simultaneously activates JNK and degrades ERK during stress, explaining pathway selectivity during apoptosis.\",\n      \"evidence\": \"In vitro E3 ligase reconstitution with ubiquitin, E1, E2; in vivo ubiquitination; ERK2 docking-motif mutants\",\n      \"pmids\": [\"12049732\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The identity of the E2 ubiquitin-conjugating enzyme was not determined\", \"Structural basis for how kinase and ligase domains coordinate was unknown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Multiple studies in 2001–2002 defined the regulatory network controlling MEKK1: RIP phosphorylates Ser-957/994 to activate MEKK1 for TNF-α/NF-κB signaling; PAK1 phosphorylates Ser-67 to block JNK binding; and caspase-generated 91-kDa fragment relocalization (not downstream kinase activation) drives apoptosis.\",\n      \"evidence\": \"In vitro kinase assays with phospho-site mutants; co-IP in RIP-deficient Jurkat cells; membrane-targeting of 91-kDa fragment\",\n      \"pmids\": [\"11369754\", \"12228228\", \"11782455\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"The phosphatase that dephosphorylates Ser-67 upon stress was not identified\", \"Whether RIP-mediated activation and caspase cleavage are sequential or alternative was unclear\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"In vivo cardiac studies showed MEKK1 is required for pressure overload-induced JNK activation and Gαq-mediated cardiac hypertrophy, establishing a non-redundant physiological role in the heart.\",\n      \"evidence\": \"MEKK1 KO mice with aortic banding and Gαq transgenic cross; JNK activity, echocardiography, ANF expression\",\n      \"pmids\": [\"12122119\", \"11891332\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MEKK1 kinase or E3 ligase activity mediates the cardiac phenotype was not dissected\", \"Downstream transcriptional targets in hypertrophy beyond ANF were not characterized\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identifying RhoA-GTP as a direct activator and Axin as a scaffold partner of MEKK1 connected it to cytoskeletal Rho signaling and the Wnt pathway, while demonstrating that MEKK1 drives uPA expression for cell migration/invasion revealed its role in tissue remodeling.\",\n      \"evidence\": \"In vitro binding/kinase assays with RhoA and PHD mutants; Axin co-IP in MEKK1−/− MEFs; uPA activity in KO fibroblasts with rescue\",\n      \"pmids\": [\"14581471\", \"12878610\", \"12493778\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RhoA activates MEKK1 in the context of focal adhesions was not shown\", \"The Axin–MEKK1 binding site on MEKK1 was not mapped\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Extending the E3 ligase substrates to c-Jun and Fra-2 showed that MEKK1 remodels the AP-1 transcription factor repertoire: it ubiquitinates and degrades c-Jun and Fra-2, while suppressing JunB mRNA, thereby sculpting AP-1 composition to control uPA expression and apoptotic sensitivity.\",\n      \"evidence\": \"In vitro/in vivo ubiquitination of c-Jun; MEKK1−/− cells with elevated c-Jun/JunB; Fra-2 ubiquitination assay; AP-1 and uPA reporter\",\n      \"pmids\": [\"17101801\", \"15558021\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether additional AP-1 family members are MEKK1 E3 substrates was not tested\", \"The relative contribution of kinase vs. ligase activity to AP-1 remodeling was not fully separated\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identifying DJ-1 as a cytoplasmic sequestrator of MEKK1 that inhibits its kinase activity, with the Parkinson-associated L166P mutant losing this ability, linked MEKK1 regulation to neurodegeneration.\",\n      \"evidence\": \"Co-IP, in vitro kinase assay, subcellular fractionation, immunofluorescence with DJ-1 KD and L166P mutant\",\n      \"pmids\": [\"18309325\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether DJ-1 loss contributes to dopaminergic neuron death via MEKK1 in vivo was not tested\", \"The DJ-1 binding site on MEKK1 was not mapped\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"In vivo metastasis studies confirmed that MEKK1 controls tumor cell dissemination through uPA and gelatinase regulation, establishing a physiological role for the MEKK1–uPA axis in cancer progression.\",\n      \"evidence\": \"MEKK1−/− × PyMT transgenic mice; lung metastasis quantification; uPA/gelatinase assays; siRNA in MDA-MB-231 cells\",\n      \"pmids\": [\"16568086\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether kinase or E3 ligase activity of MEKK1 drives the metastatic phenotype was not determined\", \"Human tumor validation beyond siRNA in cell lines was limited\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Compound mutant mouse studies showed MEKK1 preferentially phosphorylates JNK1 over JNK2 via MKK4 to control eyelid closure morphogenesis, demonstrating isoform selectivity in a developmental context.\",\n      \"evidence\": \"Mekk1/Jnk1/Jnk2 compound mutant mice; JNK isoform phosphorylation; c-Jun and PAI1 readouts\",\n      \"pmids\": [\"18032450\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis for JNK1 preference was not resolved\", \"Whether MKK7 also contributes to eyelid closure was not addressed\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Placing MEKK1 downstream of TRAF6/IPS-1 in the RIG-I/MDA5 innate antiviral pathway showed that MEKK1 is required for IFN-β induction, extending its role to innate immunity.\",\n      \"evidence\": \"TRAF6−/− and TAK1−/− MEFs; MEKK1 siRNA; MEKK1+IRF3 co-expression; IFN-β reporter\",\n      \"pmids\": [\"18984593\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MEKK1 directly phosphorylates IRF3 or acts through an intermediate kinase was not determined\", \"Redundancy with other MAP3Ks in antiviral signaling was incompletely explored\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Patient mutation studies established that MAP3K1 gain-of-function mutations cause 46,XY disorders of sex development by enhancing RHOA/MAP3K4/FRAT1 binding and reducing RAC1 binding, shifting signaling toward WNT/β-catenin/FOXL2 and away from SOX9/FGF9, while Axin-MEKK1 interaction was shown to require E3 ligase (not kinase) activity for Wnt-driven transcription.\",\n      \"evidence\": \"Linkage analysis and sequencing in DSD families; phospho-p38/ERK assays; co-IP for RHOA/RAC1/MAP3K4/FRAT1; Axin co-IP with ligase/kinase mutants; TCF/LEF reporter\",\n      \"pmids\": [\"21129722\", \"24135036\", \"20128690\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether mutations affect MEKK1 E3 ligase activity specifically was not tested\", \"The mechanism by which altered RHOA binding shifts downstream pathway selection was not fully resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"MAP3K1 deficiency causes JNK-independent retinal defects including Müller glia overproduction through cyclin D1/CDK4/6-RB-E2F dysregulation, revealing a kinase-cascade-independent developmental role.\",\n      \"evidence\": \"Map3k1 KO mice; BrdU, TUNEL, cell-type immunostaining; compound mutants with Jnk1−/− and Jnk1/2 hemizygotes\",\n      \"pmids\": [\"21862560\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the E3 ligase activity mediates the retinal phenotype was not tested\", \"Direct substrates controlling cyclin D1 were not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"CRISPR knockout of MAP3K1 in PIK3CA-mutant breast cancer cells revealed that MAP3K1 normally promotes IRS-1 degradation via JNK signaling; its loss stabilizes IRS-1 and enhances PI3Kα/AKT signaling, explaining the frequent co-occurrence of MAP3K1 and PIK3CA mutations in breast cancer.\",\n      \"evidence\": \"CRISPR KO; phospho-AKT/IRS-1 immunoblotting; IRS-1/p85 co-IP; 3D acinar growth; xenograft studies\",\n      \"pmids\": [\"29765551\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether MEKK1 E3 ligase activity directly ubiquitinates IRS-1 was not tested\", \"Clinical validation of combined PI3Kα inhibitor sensitivity in MAP3K1-mutant tumors was not provided\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the structural basis for how the kinase and E3 ligase domains of MEKK1 are coordinately regulated, the identity of the E2 enzyme(s) for its ubiquitin ligase activity, and the mechanism by which DSD-associated mutations alter the balance between RHOA and RAC1 binding at the structural level.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No crystal or cryo-EM structure of full-length MEKK1 or its PHD/RING domain in complex with substrates\", \"E2 ubiquitin-conjugating enzyme identity unknown\", \"Structural mechanism of DSD mutation-induced binding partner switching unresolved\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 3, 16, 17, 18]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 3, 35]},\n      {\"term_id\": \"GO:0016874\", \"supporting_discovery_ids\": [12, 23, 26, 31]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 10, 36]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [5, 6, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [8]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 13]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 2, 7, 9, 14, 15, 18, 30]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [1, 4, 5, 13, 23]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [29]},\n      {\"term_id\": \"R-HSA-392499\", \"supporting_discovery_ids\": [12, 23, 26]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [27, 30, 32, 34]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"MKK4\", \"JNK1\", \"ERK2\", \"RHOA\", \"AXIN1\", \"RIPK1\", \"ACTN1\", \"DJ-1\"],\n    \"other_free_text\": []\n  }\n}\n```"}