{"gene":"MAPK7","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":1995,"finding":"BMK1/MAPK7 (ERK5) was identified as a new human MAP kinase of 816 amino acids with the dual phosphorylation TEY motif characteristic of MAP kinases, but with a distinct C-terminal domain and loop-12 structure compared to other mammalian MAP kinases, suggesting it regulates signaling events distinct from the ERK group.","method":"cDNA cloning, primary structure analysis","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 — original cloning paper with structural characterization; foundational discovery replicated across the field","pmids":["7646528"],"is_preprint":false},{"year":1998,"finding":"EGF activates BMK1/ERK5 independently of Ras through the MAP kinase kinase MEK5, and expression of a dominant-negative BMK1 blocks EGF-induced cell proliferation and S-phase entry, establishing BMK1 as part of a distinct MAP kinase signaling pathway required for EGF-induced cell proliferation.","method":"Dominant-negative overexpression, kinase activity assays, cell cycle analysis","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 — dominant-negative approach with cell cycle readout; high-citation foundational paper replicated across labs","pmids":["9790194"],"is_preprint":false},{"year":2000,"finding":"ERK5 was isolated in a yeast two-hybrid screen using the MADS-MEF2 domain of MEF2D as bait; the C-terminal region of ERK5 contains both a MEF2-interacting domain and a potent transcriptional activation domain required for coactivation of MEF2D, revealing ERK5 as a MAP kinase with intrinsic transcriptional activation capability.","method":"Yeast two-hybrid, domain deletion analysis, luciferase reporter assays, endogenous gene activation","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 1–2 — yeast two-hybrid discovery confirmed by functional reporter assays and endogenous gene activation; widely replicated","pmids":["11046135"],"is_preprint":false},{"year":2001,"finding":"During retrograde neurotrophin signaling, endocytosed Trk receptors activate the ERK5 pathway, leading to nuclear translocation of ERK5, phosphorylation of CREB, and enhanced neuronal survival; ERK1/2 does not transmit this retrograde signal, establishing a unique function for ERK5 in retrograde signaling.","method":"Dominant-negative ERK5 expression, compartmentalized neuron culture, nuclear translocation imaging, CREB phosphorylation assay, survival assay","journal":"Nature neuroscience","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods in compartmentalized neurons; high-citation paper with mechanistic pathway placement","pmids":["11544482"],"is_preprint":false},{"year":2001,"finding":"EGF-induced activation of MKK5 and ERK5 occurs subsequent to activation of ERK1 and ERK2 in HeLa cells, and the ERK1/2 cascade negatively controls the MKK5/ERK5 pathway; ERK5 is not a significant activator of MAPK-activated protein kinase-1/RSK in HeLa cells.","method":"Phospho-specific antibodies, MEK inhibitor dose-response (U0126, PD184352), kinase activity assays","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 — phospho-antibody-based kinetic analysis with pharmacological inhibitors; single lab but multiple approaches","pmids":["11478941"],"is_preprint":false},{"year":2002,"finding":"Erk5 knockout mice die around E9.5–10.5 with defective blood vessel and cardiac development; endothelial cells lining the developing myocardium display disorganized, rounded morphology, and blood vessel investment with smooth muscle cells is attenuated, establishing an essential role for Erk5 in cardiovascular development and angiogenesis.","method":"Gene knockout in mice, histological and morphological analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — genetic loss-of-function with defined cardiovascular phenotype; replicated by multiple independent knockout studies","pmids":["12093914"],"is_preprint":false},{"year":2003,"finding":"ERK5 knockout mice die at approximately E10.5 with increased apoptosis in cephalic mesenchyme, vascular remodeling defects, cardiac development abnormalities, and placental defects, confirming that ERK5 is essential for early embryonic development and normal vascular system development.","method":"Gene targeting/knockout in mice, in situ hybridization, apoptosis analysis","journal":"BMC developmental biology","confidence":"High","confidence_rationale":"Tier 2 — independent replication of ERK5 knockout lethality with additional mechanistic detail on apoptosis","pmids":["14675480"],"is_preprint":false},{"year":2003,"finding":"WNK1 activates ERK5 through an MEKK2/3-dependent mechanism: WNK1 co-immunoprecipitates with MEKK2 and MEKK3, phosphorylates both in vitro, and WNK1-driven ERK5 activation is blocked by dominant-negative MEKK2/3 or MEK5; siRNA knockdown of WNK1 attenuates EGF-induced ERK5 activation, placing WNK1 upstream of MEKK2/3 in the ERK5 pathway.","method":"Co-immunoprecipitation, dominant-negative overexpression, in vitro kinase assay, siRNA knockdown","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro kinase assay plus Co-IP plus epistasis by dominant-negative and siRNA; multiple orthogonal methods","pmids":["14681216"],"is_preprint":false},{"year":2003,"finding":"Activation of the MEK5-ERK5 pathway causes phosphorylation and stabilization of c-Fos and Fra-1, with the C-terminal half of ERK5 required for maximal transactivation activity of c-Fos and Fra-1; ERK5-mediated phosphorylation of c-Fos occurs at sites distinct from those targeted by ERK1/2.","method":"Constitutively active MEK5 expression, phosphorylation mapping, reporter assays","journal":"Genes to cells : devoted to molecular & cellular mechanisms","confidence":"Medium","confidence_rationale":"Tier 2 — phosphorylation site mapping plus functional reporter assays; single lab","pmids":["12622723"],"is_preprint":false},{"year":2003,"finding":"The full-length MEK5α splice variant, but not MEK5β, activates BMK1/ERK5 and induces nuclear translocation; MEK5β acts as a dominant negative by binding BMK1 and preventing MEK5α association with BMK1, revealing splice variant-dependent control of ERK5 activation.","method":"Co-immunoprecipitation, dominant-negative and constitutively active constructs, MEF2 reporter assays, kinase activation assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — reciprocal Co-IP plus functional reporter assays with mutagenesis; multiple orthogonal approaches","pmids":["14583600"],"is_preprint":false},{"year":2004,"finding":"Conditional ablation of BMK1 in adult mice leads to lethality within 2–4 weeks, blood vessel leakage, endothelial cell rounding and apoptosis; in vitro BMK1 removal causes endothelial cell death partly through deregulation of MEF2C, a direct substrate of BMK1; endothelial-specific but not cardiomyocyte-specific deletion recapitulates cardiovascular defects.","method":"Mx1-Cre inducible conditional knockout, histology, endothelial cell culture, MEF2C substrate assay","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 — conditional genetic deletion with tissue-specific analysis and direct substrate identification (MEF2C); widely cited","pmids":["15085193"],"is_preprint":false},{"year":2001,"finding":"BMK1/ERK5 is activated via tyrosine 1062 of the RET tyrosine kinase upon GDNF stimulation or MEN2A mutation; this activation requires downstream MEK5 signaling (blocked by dominant-negative MEK5), but not RAS or PI3K pathways; activated BMK1 in turn activates the MEF2C transcription factor.","method":"Tyrosine-to-phenylalanine mutagenesis (Y1062F), kinase activity assays, MEK1/PI3K inhibitors, dominant-negative MEK5, MEF2C luciferase reporter","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — site-directed mutagenesis with pharmacological pathway dissection; single lab","pmids":["11237712"],"is_preprint":false},{"year":2005,"finding":"ERK5 drives LKLF (lung Krüppel-like factor) transcription by activating MEF2 transcription factors through its kinase and transcriptional activation domains; gene profile analysis of erk5-/- embryos and fibroblasts reconstituted with ERK5 or truncated ERK5(1-740, lacking transactivation domain) identified LKLF, flt1, and bnip3 as ERK5 target genes.","method":"Gene expression profiling (microarray) in knockout vs. reconstituted cells, shRNA/dominant-negative MEK5, ChIP-like transcription factor assays","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — genetic reconstitution approach with domain deletion and transcription factor analysis; multiple orthogonal methods","pmids":["16166637"],"is_preprint":false},{"year":2005,"finding":"The MEK5-ERK5 pathway is required for neural differentiation in Xenopus embryos: morpholino knockdown of ERK5 or MEK5 reduces head structure and inhibits neural differentiation, while forced activation of MEK5-ERK5 is sufficient to induce neural differentiation; the pathway acts downstream of SoxD and upstream of the proneural gene Xngnr1.","method":"Morpholino antisense knockdown, constitutively active MEK5 expression, epistasis analysis in Xenopus embryos","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 — morpholino knockdown plus gain-of-function plus epistasis; vertebrate ortholog study consistent with mammalian ERK5 function","pmids":["16179948"],"is_preprint":false},{"year":2006,"finding":"ERK5 binds to and phosphorylates p90 RSK: ERK5 co-immunoprecipitates with RSK from cell extracts, binds RSK in vitro, and phosphorylates RSK to activate it; the common docking (CD) domain of ERK5 and the D domain of RSK are important for their association; activation of ERK5 weakens its binding to RSK.","method":"Co-immunoprecipitation, in vitro binding assay, in vitro kinase assay, domain mutagenesis","journal":"Archives of biochemistry and biophysics","confidence":"High","confidence_rationale":"Tier 1–2 — in vitro kinase assay plus Co-IP plus domain mutagenesis; identifies RSK as direct ERK5 substrate","pmids":["16626623"],"is_preprint":false},{"year":2007,"finding":"ERK5 activation by PDGF-BB in hepatic stellate cells is Src-dependent; ERK5 silencing inhibits PDGF-BB-induced cell proliferation and c-Jun expression/activation, while ERK5 depletion increases cell migration associated with redistribution of focal contacts and decreased phosphorylation of FAK, paxillin, and PAK.","method":"siRNA knockdown, Src inhibitor, migration/proliferation assays, phosphorylation analysis","journal":"Journal of hepatology","confidence":"Medium","confidence_rationale":"Tier 2 — siRNA knockdown with defined signaling and phenotypic readouts; single lab","pmids":["17998143"],"is_preprint":false},{"year":2007,"finding":"ERK5 is activated at G2-M and required for timely mitotic entry; ERK5 activates NF-κB through RSK2-mediated phosphorylation and degradation of IκB; NF-κB inhibition at G2-M delays mitotic entry and reduces cyclin B1, cyclin B2, Plk-1, and cdc25B transcription; constitutive ERK5 activation-induced mitosis is blocked by NF-κB inhibition.","method":"Cell cycle synchronization, kinase assays, reporter assays, dominant-negative and constitutively active constructs, gene expression analysis","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — multiple epistatic approaches linking ERK5→RSK2→NF-κB→cell cycle genes with genetic rescue experiments","pmids":["17452529"],"is_preprint":false},{"year":2008,"finding":"MEK5-ERK5 pathway mediates fluid shear stress inhibition of TNF-α-induced JNK activation in endothelial cells; selective MEK5 inhibitor BIX02188 completely reversed flow inhibition of TNF-mediated JNK activation, while ERK1/2-selective inhibitor PD184352 had no effect, placing MEK5-ERK5 as the key mediator of atheroprotective flow signaling.","method":"Pharmacological inhibitors (BIX02188, PD184352), shear stress apparatus, JNK activity assay, NF-κB reporter","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 — selective inhibitor comparison with functional readout; single lab","pmids":["18358237"],"is_preprint":false},{"year":2008,"finding":"EGF-induced ERK5 activation controls Slug expression in keratinocytes; ectopic Erk5 activation increases Slug mRNA and accelerates wound healing; Erk5 shRNA knockdown reduces keratinocyte motility, Slug induction, and disrupts desmosome organization, establishing an EGFR/Erk5/Slug pathway controlling cytoskeleton organization and cell motility.","method":"Erk5 shRNA knockdown, constitutively active Erk5 expression, wound healing assay, migration assay, desmosome analysis","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — shRNA plus gain-of-function with defined pathway and phenotypic readouts; single lab","pmids":["18716062"],"is_preprint":false},{"year":2008,"finding":"MEK5-ERK5 pathway regulates apoptosis of developing thymocytes but has no function in positive selection; ERK5 activity correlates with levels of Nur77 family members but not Bim, distinguishing the ERK5 apoptosis pathway from ERK1/2 in T-cell development.","method":"Retroviral expression of dominant-negative and constitutively active MEK5, thymocyte apoptosis assays, Nur77/Bim expression analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — bidirectional genetic manipulation with defined downstream gene and phenotypic readout; genetic epistasis established","pmids":["18548009"],"is_preprint":false},{"year":2009,"finding":"Constitutive activation of MEK5/ERK5 signaling inhibits endothelial cell migration and increases focal contact area; this is associated with reduced expression of p130Cas, a key player in directed cell migration, and altered actin organization, demonstrating ERK5 controls endothelial cell migration and morphology.","method":"Retroviral gene transfer (constitutively active MEK5), migration assays, focal contact measurement, actin imaging, p130Cas expression analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — gain-of-function with defined molecular mechanism (p130Cas) and multiple phenotypic readouts; single lab","pmids":["19605361"],"is_preprint":false},{"year":2010,"finding":"ERK5 is phosphorylated during mitosis at multiple sites in its C-terminal region by CDK1 (not MEK5); CDK1 co-precipitates with ERK5 in mitotic cells; CDK1 inhibitor RO3306 reverses mitotic ERK5 phosphorylation; this CDK1-dependent phosphorylation inhibits ERK5 activity and regulates its nucleo-cytoplasmic shuttling.","method":"Co-immunoprecipitation, CDK1 inhibitor, phosphorylation site mutagenesis, nuclear/cytoplasmic fractionation","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1–2 — Co-IP plus mutagenesis plus pharmacological CDK1 inhibition; independently confirmed by a parallel study","pmids":["20736311"],"is_preprint":false},{"year":2010,"finding":"ERK5 phosphorylation during mitosis occurs at its C-terminal half (not at the TEY activation motif) and is CDK-dependent rather than MEK5-dependent; five mitotic phosphorylation sites were identified; mutagenesis showed these phosphorylations inhibit ERK5 activity and regulate ERK5 nuclear-cytoplasmic shuttling.","method":"Mass spectrometry phosphorylation site identification, mutagenesis, CDK inhibitors, fractionation assays","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 1 — MS-based phosphorylation site identification plus mutagenesis plus functional validation; corroborated by independent study","pmids":["20667468"],"is_preprint":false},{"year":2010,"finding":"BMK1/ERK5 interacts with promyelocytic leukemia protein (PML) and inhibits its tumor-suppressor function through phosphorylation; activated BMK1 inhibits PML-dependent p21 activation; a small-molecule inhibitor XMD8-92 was developed that blocks BMK1 kinase activity and suppresses tumor growth in vivo by 95%.","method":"Co-immunoprecipitation, in vitro phosphorylation assay, p21 reporter assay, xenograft tumor model, pharmacological inhibition","journal":"Cancer cell","confidence":"High","confidence_rationale":"Tier 1–2 — Co-IP plus in vitro phosphorylation plus in vivo tumor suppression with pharmacological inhibitor; multiple orthogonal methods","pmids":["20832753"],"is_preprint":false},{"year":2013,"finding":"X-ray crystal structure of the human ERK5 kinase domain in complex with a selective benzo[e]pyrimido[5,4-b]diazepine-6(11H)-one inhibitor was determined; the structure reveals specific residue differences in the ATP-binding site compared to related ERKs, p38s, and JNKs that allow development of ERK5-specific inhibitors.","method":"X-ray crystallography","journal":"Journal of medicinal chemistry","confidence":"High","confidence_rationale":"Tier 1 — crystal structure determination; provides structural basis for selective inhibitor design","pmids":["23656407"],"is_preprint":false},{"year":2013,"finding":"ERK5 is degraded through the ubiquitin-proteasome system in a process mediated by the tumor suppressor VHL through a prolyl hydroxylation-dependent mechanism; VHL-negative cell lines have elevated ERK5, and ERK5 knockdown in these cells decreases proliferation and migration.","method":"Transfection assays, endogenous ERK5 analysis in VHL-positive and -negative cell lines, proteasome inhibitor experiments, siRNA knockdown","journal":"Neoplasia (New York, N.Y.)","confidence":"Medium","confidence_rationale":"Tier 2 — VHL-dependent degradation with functional consequence; single lab with multiple cell line systems","pmids":["23730213"],"is_preprint":false},{"year":2014,"finding":"XIAP directly interacts with MEKK2/3 and competes with PB1 domain-mediated binding to MEK5; XIAP and cIAP1 conjugate predominantly K63-linked ubiquitin chains to MEKK2 and MEKK3, directly impeding MEK5-ERK5 interaction in a trimeric complex and leading to ERK5 inactivation; loss of XIAP or cIAP1 leads to hyperactivation of ERK5.","method":"Co-immunoprecipitation, ubiquitination assays, domain competition assays, ubiquitin chain linkage analysis, skeletal myoblast differentiation assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1–2 — direct interaction mapping plus K63 ubiquitination characterization plus functional consequence in differentiation; rigorous multi-method study","pmids":["24975362"],"is_preprint":false},{"year":2014,"finding":"ERK5 activation in macrophages promotes efferocytosis; macrophage-specific ERK5-null mice exhibit reduced efferocytosis and accelerated atherosclerotic plaque formation when crossed with LDL receptor-/- mice on a high-cholesterol diet; statins robustly activate ERK5 in macrophages.","method":"Macrophage-specific conditional ERK5 knockout, efferocytosis assays, atherosclerosis model (LDLR-/- mice), pharmacological ERK5 activation","journal":"Circulation","confidence":"High","confidence_rationale":"Tier 2 — cell-type-specific conditional knockout with in vivo atherosclerosis readout and mechanistic efferocytosis assays","pmids":["25001623"],"is_preprint":false},{"year":2014,"finding":"IFN-γ-mediated induction of LRRK2 in macrophages is suppressed by pharmacological inhibition and RNA interference of ERK5, establishing ERK5 as a required mediator of the IFN-γ signaling pathway inducing LRRK2 expression.","method":"ERK5 pharmacological inhibition, siRNA knockdown, LRRK2 immunostaining, differentiation of THP-1 cells and primary monocytes","journal":"Journal of neurochemistry","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological and genetic knockdown with defined pathway placement; single lab","pmids":["24479685"],"is_preprint":false},{"year":2016,"finding":"Genetic deletion of ERK1/2 in intestinal epithelial cells results in supraphysiological ERK5 pathway activity; combined pharmacological targeting of MEK1/2 and MEK5 is more effective than single treatment in suppressing proliferation in intestinal organoids and colorectal cancer lines, demonstrating ERK5 provides a bypass proliferative route when ERK1/2 is abrogated.","method":"Conditional ERK1/2 knockout mice, MEK1/2 and MEK5/ERK5 pharmacological inhibitors, intestinal organoid culture, CRC cell lines","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 — genetic deletion plus pharmacological combination; functional epistasis established in vivo and in organoids","pmids":["27187615"],"is_preprint":false},{"year":2016,"finding":"Selective ERK5 kinase inhibitors have no antiinflammatory or antiproliferative activity, whereas less selective inhibitors block both ERK5 and BET bromodomains; the source of efficacy of previously reported ERK5 inhibitors is off-target activity on bromodomains; phenotypes from genetic deletion of ERK5 likely arise from removal of a noncatalytic function.","method":"Synthesis of selective ERK5 inhibitors, bromodomain selectivity profiling (KINOMEscan, BROMOscan), cell proliferation and inflammation assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1 — rigorous selectivity profiling with functional assays demonstrating kinase-independent function; challenges prior mechanistic interpretations","pmids":["27679845"],"is_preprint":false},{"year":2016,"finding":"ERK5 maintains embryonic stem cells in the naive pluripotent state and suppresses progression toward primed pluripotency and neuroectoderm differentiation; ERK5 also inhibits a cardiomyocyte-specific differentiation program; these functions were dissected from BRD4 functions using CRISPR/Cas9 ERK5 knockout and compound selectivity engineering.","method":"CRISPR/Cas9 knockout, selective ERK5 inhibitor/BET inhibitor comparison, pluripotency state assays, differentiation assays","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 2 — CRISPR/Cas9 with compound selectivity engineering to distinguish ERK5 from BRD4 functions; multiple orthogonal approaches","pmids":["27498864"],"is_preprint":false},{"year":2017,"finding":"YAP promotes myogenic differentiation through the MEK5-ERK5 pathway; YAP activates the Abl/Src/MEKK3/MEK5/ERK5 kinase cascade; co-immunoprecipitation showed YAP interacts with MEKK3 and ERK5; MEKK3 PPGY motif (aa 178-181) mediates interaction with YAP, and Y181F mutation inhibits MEK5/ERK5 activation and myogenesis.","method":"Co-immunoprecipitation, site-directed mutagenesis, constitutive expression, kinase activation assays, myogenic differentiation assays","journal":"FASEB journal : official publication of the Federation of American Societies for Experimental Biology","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP plus mutagenesis plus functional differentiation readout; single lab","pmids":["28356344"],"is_preprint":false},{"year":2018,"finding":"Mitochondrial complex I activity induces ERK5 expression through fumarate accumulation; ERK5 in turn induces MEF2-dependent NRF2 expression, activating the antioxidant response; blocking OXPHOS decreases Erk5 and Nrf2 expression in vivo, establishing an OXPHOS-fumarate-ERK5-MEF2-NRF2 axis for antioxidant response.","method":"OXPHOS inhibition, fumarate supplementation, MEF2/NRF2 reporter assays, fibroblasts from mitochondrial disorder patients, mouse model","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — metabolic-genetic epistasis with multiple cell and animal models; single lab","pmids":["29743487"],"is_preprint":false},{"year":2018,"finding":"IFN-γ receptor stimulation activates ULK1, which interacts with and phosphorylates MLK3, leading to downstream ERK5 activation; this ULK1-MLK3-ERK5 axis is required for transcription of antiviral IFN-stimulated genes (ISGs) and IFN-γ-dependent antiviral effects, independent of autophagy.","method":"Kinase interaction assays, phosphorylation analysis, antiviral assays, gene expression analysis, pathway inhibition","journal":"Science signaling","confidence":"Medium","confidence_rationale":"Tier 2 — ULK1-MLK3 interaction identification plus functional antiviral readout; novel pathway placed by epistasis","pmids":["30459284"],"is_preprint":false},{"year":2019,"finding":"Resistance to ERK1/2 inhibitor SCH772984 in BRAFV600E melanoma cells involves stimulation of the IGF1R-MEK5-ERK5 signaling pathway, which counteracts Erk1/2 inhibition; IGF1R inhibitor linsitinib blocked Erk5 activation in resistant cells, establishing this axis as a resistance bypass route.","method":"ERKi-resistant cell line generation, pathway analysis, IGF1R inhibitor treatment, 3D spheroid assays, xenograft models","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — mechanistic pathway identification by resistance profiling with pharmacological epistasis; single lab","pmids":["30833419"],"is_preprint":false},{"year":2020,"finding":"Small molecule ERK5 kinase inhibitors paradoxically activate ERK5 transcriptional transactivation domain activity by stimulating nuclear localization of ERK5; this kinase domain occupancy-driven nuclear translocation activates the C-terminal transactivation domain independently of kinase activity.","method":"ERK5 kinase and transcriptional reporter assays, nuclear localization imaging, selective ERK5 inhibitor panel","journal":"Biochemical Society transactions","confidence":"High","confidence_rationale":"Tier 2 — kinase inhibitor-induced paradoxical activation demonstrated by dual readout (kinase vs. transcriptional); mechanistically important finding replicated across multiple inhibitors","pmids":["32915196"],"is_preprint":false},{"year":2022,"finding":"Mechanosensitive channel PIEZO1 senses shear force and activates CaMKII, which interacts with and activates MEKK3, promoting MEKK3/MEK5/ERK5 signaling and ultimately inducing KLF2/4 transcription in endothelial cells; endothelial-specific Piezo1 deletion reduces KLF2/4 expression in vivo.","method":"Endothelial-specific Piezo1 knockout mice, co-immunoprecipitation (CaMKII-MEKK3), calcium imaging, shear stress experiments, KLF2/4 expression analysis","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 2 — genetic knockout plus Co-IP plus functional pathway placement; single lab","pmids":["35883633"],"is_preprint":false},{"year":2023,"finding":"ERK5 S496 phosphorylation mediates both senescence-associated secretory phenotype (SASP) and senescence-associated stemness by upregulating AHR in macrophages; S496 phosphorylation induces NRF2 SUMOylation at K518 to inhibit NRF2 transcriptional activity without altering ERK5 catalytic activity; ERK5 S496A knock-in mice are protected from atherosclerosis.","method":"CRISPR/Cas9 knock-in (ERK5 S496A), imaging mass cytometry, bone marrow-derived macrophage isolation, RNA-seq, NRF2 SUMOylation assays, atherosclerosis model","journal":"Circulation research","confidence":"High","confidence_rationale":"Tier 1–2 — phosphomimetic knock-in mouse plus mechanistic biochemistry (NRF2 SUMOylation) plus in vivo disease model; multiple orthogonal methods","pmids":["37264926"],"is_preprint":false},{"year":2012,"finding":"BMK1 signaling suppresses epithelial-mesenchymal transition (EMT): BMK1 elevation augments E-cadherin-mediated cell-cell adhesion and reduces mesenchymal markers; BMK1 depletion promotes Snail nuclear accumulation through Akt/GSK3β signaling activated by increased DEPTOR expression (mTOR inhibitor); BMK1 depletion promotes metastasis in vivo.","method":"BMK1 overexpression and siRNA knockdown, EMT marker analysis, nuclear/cytoplasmic fractionation, DEPTOR modulation, in vivo metastasis model","journal":"Cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — bidirectional genetic manipulation with mechanistic pathway (DEPTOR/mTOR/Akt/GSK3β/Snail) and in vivo validation; single lab","pmids":["22282661"],"is_preprint":false},{"year":2017,"finding":"Dichloroacetate (DCA) increases ERK5 expression through fumarate accumulation (OXPHOS induction), which activates the transcription factor MEF2 to drive LDLR transcription and LDL intake; pharmacological or genetic inhibition of the ERK5/MEF2 pathway decreases LDLR expression and LDL uptake.","method":"DCA treatment, genetic/pharmacological ERK5/MEF2 inhibition, LDLR luciferase reporter, H3K27 acetylation ChIP, primary hepatocytes, mouse models","journal":"Scientific reports","confidence":"Medium","confidence_rationale":"Tier 2 — ChIP plus reporter assays plus multiple cell and animal models; mechanistic ERK5→MEF2→LDLR pathway established; single lab","pmids":["28878225"],"is_preprint":false},{"year":2020,"finding":"ERK5 inhibition or silencing in endometrial cancer impairs NF-κB pathway by downregulating NEMO/IKKγ expression, leading to impaired p65/RELA activity and apoptosis; overexpression of NEMO/IKKγ rescues this apoptosis, placing ERK5 upstream of NEMO in an ERK5-NEMO-NF-κB survival pathway.","method":"ERK5 siRNA/pharmacological inhibition, MEK5 genetic deletion, NEMO rescue overexpression, xenograft model, NF-κB reporter, correlation in human EC tumor samples","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 — rescue experiment (NEMO overexpression) plus xenograft validation plus human tissue correlation; single lab","pmids":["36123565"],"is_preprint":false},{"year":2021,"finding":"ERK5 inhibition induces p21-mediated cellular senescence in melanoma: genetic and pharmacological ERK5 blockade increases senescence-associated β-galactosidase activity, p21 expression, and SASP cytokines (CXCL1, CXCL8, CCL20); knockdown of p21 suppresses ERK5 inhibition-induced senescence, identifying p21 as the key mediator; confirmed in vivo in melanoma xenografts.","method":"ERK5 shRNA knockdown, XMD8-92 pharmacological inhibition, transcriptomic analysis, senescence assays (β-galactosidase), p21 siRNA rescue, xenograft model","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 — bidirectional genetic manipulation plus pharmacology plus transcriptomics plus rescue experiment plus in vivo validation; multiple orthogonal methods","pmids":["34799355"],"is_preprint":false},{"year":2020,"finding":"MEK5/ERK5 inhibition in macrophages reduces IL-4-induced M2 differentiation (Arg-1, Ym-1, Fizz-1 expression) independently of STAT3/STAT6 phosphorylation, but through decreased c-Myc expression; myeloid-specific Erk5 conditional knockout (LysMcre/Erk5f/f) confirms ERK5 requirement for IL-4-induced M2 polarization.","method":"MEK5/ERK5 pharmacological inhibition, myeloid-specific conditional ERK5 knockout, M2 marker analysis, STAT3/STAT6 phosphorylation, c-Myc expression analysis","journal":"Journal of leukocyte biology","confidence":"High","confidence_rationale":"Tier 2 — conditional cell-type-specific knockout plus pharmacological confirmation plus mechanistic exclusion (STAT independence); multiple methods","pmids":["32745297"],"is_preprint":false}],"current_model":"MAPK7/ERK5 is a unique MAP kinase activated by the MEK5 kinase (upstream regulated by MEKK2/3, WNK1, and PIEZO1-CaMKII) that contains both an N-terminal kinase domain (activated by MEK5-mediated dual TEY phosphorylation) and a C-terminal transcriptional activation domain that directly coactivates MEF2 transcription factors to drive target gene expression (including KLF2, LKLF, NRF2, and c-Jun); during mitosis, CDK1 phosphorylates ERK5 at multiple C-terminal sites independently of MEK5 to regulate ERK5 nucleo-cytoplasmic shuttling and suppress its activity; ERK5 phosphorylates direct substrates including MEF2C, PML (inhibiting its tumor suppressor function), and RSK (activating it through its CD domain interaction), and is inactivated by XIAP/cIAP1-mediated K63-linked ubiquitination of MEKK2/3; physiologically, ERK5 signaling is essential for cardiovascular development, endothelial cell survival and vascular integrity, retrograde neurotrophin signaling, and immune cell differentiation (macrophage efferocytosis, M2 polarization, thymocyte apoptosis), while paradoxically, selective kinase inhibitors activate ERK5's transcriptional domain through nuclear translocation, indicating that many biological functions attributed to ERK5 arise from its non-catalytic transcriptional activity rather than kinase activity alone."},"narrative":{"teleology":[{"year":1995,"claim":"Identification of ERK5/BMK1 as a structurally distinct MAP kinase with a unique C-terminal extension established that an additional mammalian MAPK cascade existed beyond ERK1/2, JNK, and p38.","evidence":"cDNA cloning and primary structure analysis revealing 816-aa protein with TEY motif and distinctive loop-12/C-terminal domain","pmids":["7646528"],"confidence":"High","gaps":["No activating kinase or physiological stimulus identified","Function of C-terminal extension unknown"]},{"year":1998,"claim":"Demonstration that MEK5 activates ERK5 in response to EGF independently of Ras, and that dominant-negative ERK5 blocks EGF-induced proliferation, established ERK5 as a functionally distinct MAPK cascade required for mitogenic signaling.","evidence":"Dominant-negative ERK5 overexpression blocking EGF-induced S-phase entry; kinase activity assays in multiple cell types","pmids":["9790194"],"confidence":"High","gaps":["Upstream kinases activating MEK5 not identified","Direct substrates of ERK5 unknown"]},{"year":2000,"claim":"Discovery that ERK5's C-terminal region contains an intrinsic transcriptional activation domain and directly coactivates MEF2 transcription factors revealed a dual kinase/transcription factor architecture unique among MAP kinases.","evidence":"Yeast two-hybrid screen with MEF2D MADS domain as bait; domain deletion and luciferase reporter assays confirming coactivation","pmids":["11046135"],"confidence":"High","gaps":["Whether transcriptional activation requires kinase activity not resolved","Target genes of ERK5-MEF2 axis not identified"]},{"year":2001,"claim":"ERK5 was placed in retrograde neurotrophin signaling (Trk→ERK5→CREB→survival) and downstream of RET/GDNF via MEK5, broadening its receptor inputs and establishing a specific role in neuronal survival distinct from ERK1/2.","evidence":"Compartmentalized neuron cultures with dominant-negative ERK5 blocking retrograde survival; RET Y1062F mutagenesis abolishing ERK5 activation","pmids":["11544482","11237712"],"confidence":"High","gaps":["Direct phosphorylation of CREB by ERK5 not demonstrated","Whether ERK5 transcriptional domain contributes to neuronal survival unknown"]},{"year":2002,"claim":"ERK5 knockout mice dying at E9.5–10.5 with severe cardiovascular defects established ERK5 as essential for vascular development and cardiac morphogenesis in vivo.","evidence":"Constitutive Erk5 gene knockout in mice with histological analysis showing endothelial disorganization and vascular remodeling failure","pmids":["12093914","14675480"],"confidence":"High","gaps":["Cell-type-specific contributions (endothelial vs. cardiomyocyte) not resolved by constitutive knockout","Whether kinase activity or transcriptional domain mediates developmental function unknown"]},{"year":2003,"claim":"Identification of WNK1→MEKK2/3→MEK5 as the upstream kinase cascade and MEK5α/β splice variant regulation defined the complete four-tier kinase module activating ERK5.","evidence":"Co-IP of WNK1 with MEKK2/3, in vitro phosphorylation, siRNA knockdown of WNK1 reducing EGF-induced ERK5 activation; MEK5α vs. MEK5β differential binding to ERK5","pmids":["14681216","14583600"],"confidence":"High","gaps":["Physiological contexts where WNK1 is the dominant ERK5 activator not defined","How MEK5 splice variant ratio is regulated unknown"]},{"year":2004,"claim":"Conditional ERK5 deletion in adult mice causing endothelial apoptosis, blood vessel leakage, and lethality within weeks—with MEF2C identified as a direct substrate—demonstrated that ERK5 is continuously required for adult vascular integrity through MEF2C phosphorylation.","evidence":"Mx1-Cre inducible conditional knockout; endothelial-specific deletion recapitulating phenotype; in vitro MEF2C substrate assay","pmids":["15085193"],"confidence":"High","gaps":["Full spectrum of MEF2C target genes downstream of ERK5 in endothelium not mapped","Relative contribution of kinase vs. transcriptional domain to endothelial survival not resolved"]},{"year":2005,"claim":"Identification of LKLF/KLF2 as a direct transcriptional target of ERK5-MEF2 axis (requiring both kinase and C-terminal transactivation domains) established the key downstream effector genes mediating ERK5 vascular and anti-inflammatory functions.","evidence":"Gene expression profiling of erk5−/− embryos reconstituted with full-length vs. C-terminally truncated ERK5","pmids":["16166637"],"confidence":"High","gaps":["ChIP evidence for direct MEF2 occupancy at LKLF promoter not shown","Whether LKLF alone accounts for vascular phenotype not tested"]},{"year":2006,"claim":"ERK5 was shown to directly phosphorylate and activate RSK through CD domain–D domain interaction, and to promote NF-κB activation via RSK2-mediated IκB degradation at G2-M, connecting ERK5 to cell cycle progression and NF-κB signaling.","evidence":"In vitro kinase assay, Co-IP, domain mutagenesis for ERK5-RSK; cell cycle synchronization linking ERK5→RSK2→NF-κB→cyclin B1 transcription","pmids":["16626623","17452529"],"confidence":"High","gaps":["Whether RSK is a major physiological ERK5 substrate in vivo not established","NF-κB dependence observed in one cell system"]},{"year":2008,"claim":"ERK5 was placed in atheroprotective shear stress signaling (MEK5-ERK5 mediating flow-dependent JNK suppression) and in thymocyte apoptosis regulation via Nur77, extending ERK5 functions to mechanosensing and immune cell development.","evidence":"Selective MEK5 inhibitor BIX02188 in endothelial shear stress assay; dominant-negative/constitutively active MEK5 in thymocyte apoptosis with Nur77 expression analysis","pmids":["18358237","18548009"],"confidence":"High","gaps":["Mechanosensor upstream of MEK5-ERK5 in shear stress not identified at this point","Whether ERK5 directly phosphorylates Nur77 not tested"]},{"year":2010,"claim":"Discovery that CDK1 phosphorylates ERK5 at multiple C-terminal sites during mitosis—independently of MEK5—to inhibit ERK5 and regulate its nuclear-cytoplasmic shuttling revealed a non-canonical regulation mechanism decoupling mitotic ERK5 phosphorylation from its activation.","evidence":"Mass spectrometry identification of five mitotic phosphorylation sites; CDK1 Co-IP with ERK5; CDK1 inhibitor RO3306 reversing phosphorylation; mutagenesis validating functional consequences","pmids":["20736311","20667468"],"confidence":"High","gaps":["Functional consequence of CDK1-mediated ERK5 inhibition during mitosis not fully defined","Whether CDK1 phosphorylation affects C-terminal transcriptional domain directly not tested"]},{"year":2010,"claim":"Identification of PML as a direct ERK5 substrate whose tumor-suppressor function (p21 induction) is inhibited by ERK5 phosphorylation provided a direct oncogenic mechanism, validated by the ERK5 inhibitor XMD8-92 suppressing tumor growth in vivo.","evidence":"Co-IP of ERK5 with PML, in vitro phosphorylation, p21 reporter suppression, xenograft tumor model with 95% growth suppression by XMD8-92","pmids":["20832753"],"confidence":"High","gaps":["PML phosphorylation sites by ERK5 not mapped","XMD8-92 selectivity later questioned (bromodomain off-targets)"]},{"year":2014,"claim":"XIAP and cIAP1 were identified as negative regulators of ERK5 signaling through K63-linked ubiquitination of MEKK2/3, which disrupts the MEKK2/3-MEK5 interaction, revealing a ubiquitin-dependent mechanism that restrains ERK5 pathway activation.","evidence":"Co-IP, K63-linked ubiquitin chain analysis, PB1 domain competition assays, skeletal myoblast differentiation readout","pmids":["24975362"],"confidence":"High","gaps":["Physiological triggers that relieve XIAP/cIAP1-mediated suppression not identified","Whether K63 ubiquitination also affects MEKK2/3 stability not tested"]},{"year":2014,"claim":"Macrophage-specific ERK5 deletion revealed ERK5 is required for efferocytosis and protection from atherosclerosis, while ERK5 also mediates IFN-γ-induced LRRK2 expression, establishing ERK5 as a central node in macrophage immune function.","evidence":"Macrophage-specific conditional ERK5 knockout crossed to LDLR−/− mice; efferocytosis assays; ERK5 siRNA and inhibitor reducing LRRK2 induction","pmids":["25001623","24479685"],"confidence":"High","gaps":["Direct ERK5 substrates mediating efferocytosis not identified","Whether kinase activity or transcriptional domain required for macrophage functions not distinguished"]},{"year":2016,"claim":"The landmark finding that selective ERK5 kinase inhibitors lack antiproliferative or anti-inflammatory activity—and that prior inhibitor efficacy derived from off-target bromodomain inhibition—established that ERK5's major biological functions depend on its non-catalytic transcriptional domain rather than kinase activity alone.","evidence":"Synthesis of highly selective ERK5 inhibitors; KINOMEscan and BROMOscan profiling demonstrating bromodomain cross-reactivity of XMD8-92 and BIX02189; functional assays showing no effect of selective kinase inhibition","pmids":["27679845"],"confidence":"High","gaps":["Whether any ERK5 kinase substrates are physiologically relevant remains uncertain","Mechanism by which kinase domain occupancy affects C-terminal domain not resolved"]},{"year":2016,"claim":"ERK5 maintains naive pluripotency in embryonic stem cells and suppresses neuroectoderm/cardiomyocyte differentiation, with CRISPR knockout distinguishing ERK5-specific from BRD4-dependent functions; concurrently, ERK5 was shown to serve as a bypass proliferative route when ERK1/2 is deleted in intestinal epithelium.","evidence":"CRISPR/Cas9 ERK5 knockout in ESCs with selective compound comparison; conditional ERK1/2 knockout in intestinal epithelium with MEK5 inhibitor combination in organoids and CRC lines","pmids":["27498864","27187615"],"confidence":"High","gaps":["Transcriptional targets of ERK5 in pluripotency maintenance not defined","Whether ERK5 bypass in ERK1/2-null cells requires kinase activity not tested"]},{"year":2020,"claim":"The paradox that ERK5 kinase inhibitors activate ERK5's transcriptional domain by promoting nuclear translocation explained why kinase inhibition fails to recapitulate genetic deletion phenotypes, fundamentally reframing therapeutic targeting strategies for ERK5.","evidence":"Panel of selective ERK5 inhibitors tested with dual kinase activity and transcriptional reporter assays; nuclear localization imaging","pmids":["32915196"],"confidence":"High","gaps":["Structural mechanism linking kinase domain occupancy to conformational change enabling nuclear import not resolved","Whether degrader approaches can overcome paradoxical activation not tested"]},{"year":2020,"claim":"ERK5 was shown to be required for IL-4-induced M2 macrophage polarization through c-Myc (independently of STAT3/STAT6), expanding its immune functions beyond efferocytosis to alternative macrophage activation.","evidence":"Myeloid-specific conditional ERK5 knockout (LysMcre/Erk5f/f) plus MEK5/ERK5 pharmacological inhibition; M2 marker and c-Myc expression analysis","pmids":["32745297"],"confidence":"High","gaps":["Whether ERK5 directly regulates c-Myc transcription or stability not resolved","In vivo consequence of ERK5-dependent M2 polarization defect not tested"]},{"year":2022,"claim":"PIEZO1 was identified as the mechanosensor upstream of ERK5 in endothelial shear stress signaling, activating CaMKII which directly interacts with MEKK3 to drive MEKK3/MEK5/ERK5-dependent KLF2/4 transcription, completing the mechanotransduction pathway from membrane to nucleus.","evidence":"Endothelial-specific Piezo1 knockout mice; CaMKII-MEKK3 Co-IP; calcium imaging; shear stress experiments measuring KLF2/4","pmids":["35883633"],"confidence":"Medium","gaps":["CaMKII phosphorylation site on MEKK3 not mapped","Whether PIEZO1-ERK5 axis operates in non-endothelial mechanosensing contexts unknown"]},{"year":2023,"claim":"ERK5 S496 phosphorylation was identified as a switch controlling senescence-associated secretory phenotype and stemness in macrophages by inducing NRF2 SUMOylation at K518, with S496A knock-in mice protected from atherosclerosis, providing the first phosphosite-specific in vivo ERK5 disease mechanism.","evidence":"CRISPR/Cas9 S496A knock-in mice; imaging mass cytometry; NRF2 SUMOylation assays; atherosclerosis model","pmids":["37264926"],"confidence":"High","gaps":["Kinase responsible for S496 phosphorylation not identified","Whether S496 phosphorylation affects ERK5 transcriptional domain function not tested","Generalizability of S496-NRF2 SUMOylation axis beyond macrophages unknown"]},{"year":null,"claim":"The central unresolved question is how to therapeutically target ERK5 given that kinase inhibition paradoxically activates its transcriptional domain; additionally, the structural basis for how kinase domain occupancy triggers conformational opening and nuclear translocation, the relative contributions of kinase versus transcriptional functions across different tissues, and the identity of the kinase that phosphorylates ERK5 at S496 remain unknown.","evidence":"","pmids":[],"confidence":"High","gaps":["Structural mechanism coupling kinase domain occupancy to C-terminal conformational change and nuclear import not determined","No ERK5-selective degrader or dual kinase/transcription-domain inhibitor reported","Kinase phosphorylating S496 unknown","Comprehensive in vivo substrate repertoire for ERK5 kinase activity not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[1,10,14,23]},{"term_id":"GO:0140110","term_label":"transcription regulator activity","supporting_discovery_ids":[2,12,36]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,14,23]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[3,9,21,36]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[21,22]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,7,9,26,37]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[5,6,13]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[16,21,22]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[10,19]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[19,27,43]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[2,12,36]}],"complexes":[],"partners":["MEK5","MEKK2","MEKK3","MEF2C","MEF2D","PML","RPS6KA1","CDK1"],"other_free_text":[]},"mechanistic_narrative":"MAPK7 (ERK5/BMK1) is an atypical MAP kinase that integrates mitogenic, mechanical, and stress signals to regulate cardiovascular development, immune cell function, cell proliferation, and differentiation through both catalytic and non-catalytic mechanisms. Activated by MEK5-mediated dual TEY phosphorylation downstream of MEKK2/3 (itself regulated by WNK1, PIEZO1-CaMKII, and XIAP/cIAP1-mediated K63 ubiquitination), ERK5 phosphorylates substrates including MEF2C, PML, and RSK, and uniquely possesses a C-terminal transcriptional activation domain that directly coactivates MEF2 transcription factors to drive expression of KLF2, NRF2, LKLF, and c-Jun [PMID:11046135, PMID:16166637, PMID:20832753, PMID:16626623, PMID:14681216]. During mitosis, CDK1 phosphorylates ERK5 at C-terminal sites independently of MEK5, inhibiting its activity and regulating nucleo-cytoplasmic shuttling, while selective kinase inhibitors paradoxically activate ERK5's transcriptional domain through forced nuclear translocation, demonstrating that many biological functions attributed to ERK5—including roles in endothelial survival, embryonic vascular development, macrophage efferocytosis, M2 polarization, and stem cell pluripotency—arise substantially from its non-catalytic transcriptional activity [PMID:20736311, PMID:27679845, PMID:32915196, PMID:12093914, PMID:25001623, PMID:27498864]. ERK5 S496 phosphorylation drives senescence-associated phenotypes in macrophages via NRF2 SUMOylation and AHR upregulation, and knock-in mice bearing an S496A mutation are protected from atherosclerosis [PMID:37264926]."},"prefetch_data":{"uniprot":{"accession":"Q13164","full_name":"Mitogen-activated protein kinase 7","aliases":["Big MAP kinase 1","BMK-1","Extracellular signal-regulated kinase 5","ERK-5"],"length_aa":816,"mass_kda":88.4,"function":"Plays a role in various cellular processes such as proliferation, differentiation and cell survival. The upstream activator of MAPK7 is the MAPK kinase MAP2K5. Upon activation, it translocates to the nucleus and phosphorylates various downstream targets including MEF2C. EGF activates MAPK7 through a Ras-independent and MAP2K5-dependent pathway. As part of the MAPK/ERK signaling pathway, acts as a negative regulator of apoptosis in cardiomyocytes via interaction with STUB1/CHIP and promotion of STUB1-mediated ubiquitination and degradation of ICER-type isoforms of CREM (By similarity). May have a role in muscle cell differentiation. May be important for endothelial function and maintenance of blood vessel integrity. MAP2K5 and MAPK7 interact specifically with one another and not with MEK1/ERK1 or MEK2/ERK2 pathways. Phosphorylates SGK1 at Ser-78 and this is required for growth factor-induced cell cycle progression. Involved in the regulation of p53/TP53 by disrupting the PML-MDM2 interaction","subcellular_location":"Cytoplasm; Nucleus; Nucleus, PML body","url":"https://www.uniprot.org/uniprotkb/Q13164/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/MAPK7","classification":"Not Classified","n_dependent_lines":7,"n_total_lines":1208,"dependency_fraction":0.005794701986754967},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"FKBP5","stoichiometry":0.2},{"gene":"SNRPA","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/MAPK7","total_profiled":1310},"omim":[{"mim_id":"612117","title":"MICRO RNA 143; MIR143","url":"https://www.omim.org/entry/612117"},{"mim_id":"609487","title":"MITOGEN-ACTIVATED PROTEIN KINASE KINASE KINASE 2; MAP3K2","url":"https://www.omim.org/entry/609487"},{"mim_id":"609479","title":"MITOGEN-ACTIVATED PROTEIN KINASE KINASE KINASE 20; MAP3K20","url":"https://www.omim.org/entry/609479"},{"mim_id":"604439","title":"GRB2-ASSOCIATED BINDING PROTEIN 1; GAB1","url":"https://www.omim.org/entry/604439"},{"mim_id":"602521","title":"MITOGEN-ACTIVATED PROTEIN KINASE 7; MAPK7","url":"https://www.omim.org/entry/602521"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/MAPK7"},"hgnc":{"alias_symbol":["BMK1","ERK5"],"prev_symbol":["PRKM7"]},"alphafold":{"accession":"Q13164","domains":[{"cath_id":"3.30.200.20","chopping":"43-139_373-378","consensus_level":"medium","plddt":88.9882,"start":43,"end":378},{"cath_id":"1.10.510.10","chopping":"140-358","consensus_level":"medium","plddt":92.2746,"start":140,"end":358}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13164","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q13164-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q13164-F1-predicted_aligned_error_v6.png","plddt_mean":65.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=MAPK7","jax_strain_url":"https://www.jax.org/strain/search?query=MAPK7"},"sequence":{"accession":"Q13164","fasta_url":"https://rest.uniprot.org/uniprotkb/Q13164.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q13164/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q13164"}},"corpus_meta":[{"pmid":"9790194","id":"PMC_9790194","title":"Bmk1/Erk5 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dual phosphorylation TEY motif characteristic of MAP kinases, but with a distinct C-terminal domain and loop-12 structure compared to other mammalian MAP kinases, suggesting it regulates signaling events distinct from the ERK group.\",\n      \"method\": \"cDNA cloning, primary structure analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — original cloning paper with structural characterization; foundational discovery replicated across the field\",\n      \"pmids\": [\"7646528\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"EGF activates BMK1/ERK5 independently of Ras through the MAP kinase kinase MEK5, and expression of a dominant-negative BMK1 blocks EGF-induced cell proliferation and S-phase entry, establishing BMK1 as part of a distinct MAP kinase signaling pathway required for EGF-induced cell proliferation.\",\n      \"method\": \"Dominant-negative overexpression, kinase activity assays, cell cycle analysis\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — dominant-negative approach with cell cycle readout; high-citation foundational paper replicated across labs\",\n      \"pmids\": [\"9790194\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"ERK5 was isolated in a yeast two-hybrid screen using the MADS-MEF2 domain of MEF2D as bait; the C-terminal region of ERK5 contains both a MEF2-interacting domain and a potent transcriptional activation domain required for coactivation of MEF2D, revealing ERK5 as a MAP kinase with intrinsic transcriptional activation capability.\",\n      \"method\": \"Yeast two-hybrid, domain deletion analysis, luciferase reporter assays, endogenous gene activation\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — yeast two-hybrid discovery confirmed by functional reporter assays and endogenous gene activation; widely replicated\",\n      \"pmids\": [\"11046135\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"During retrograde neurotrophin signaling, endocytosed Trk receptors activate the ERK5 pathway, leading to nuclear translocation of ERK5, phosphorylation of CREB, and enhanced neuronal survival; ERK1/2 does not transmit this retrograde signal, establishing a unique function for ERK5 in retrograde signaling.\",\n      \"method\": \"Dominant-negative ERK5 expression, compartmentalized neuron culture, nuclear translocation imaging, CREB phosphorylation assay, survival assay\",\n      \"journal\": \"Nature neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods in compartmentalized neurons; high-citation paper with mechanistic pathway placement\",\n      \"pmids\": [\"11544482\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"EGF-induced activation of MKK5 and ERK5 occurs subsequent to activation of ERK1 and ERK2 in HeLa cells, and the ERK1/2 cascade negatively controls the MKK5/ERK5 pathway; ERK5 is not a significant activator of MAPK-activated protein kinase-1/RSK in HeLa cells.\",\n      \"method\": \"Phospho-specific antibodies, MEK inhibitor dose-response (U0126, PD184352), kinase activity assays\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phospho-antibody-based kinetic analysis with pharmacological inhibitors; single lab but multiple approaches\",\n      \"pmids\": [\"11478941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Erk5 knockout mice die around E9.5–10.5 with defective blood vessel and cardiac development; endothelial cells lining the developing myocardium display disorganized, rounded morphology, and blood vessel investment with smooth muscle cells is attenuated, establishing an essential role for Erk5 in cardiovascular development and angiogenesis.\",\n      \"method\": \"Gene knockout in mice, histological and morphological analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic loss-of-function with defined cardiovascular phenotype; replicated by multiple independent knockout studies\",\n      \"pmids\": [\"12093914\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"ERK5 knockout mice die at approximately E10.5 with increased apoptosis in cephalic mesenchyme, vascular remodeling defects, cardiac development abnormalities, and placental defects, confirming that ERK5 is essential for early embryonic development and normal vascular system development.\",\n      \"method\": \"Gene targeting/knockout in mice, in situ hybridization, apoptosis analysis\",\n      \"journal\": \"BMC developmental biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — independent replication of ERK5 knockout lethality with additional mechanistic detail on apoptosis\",\n      \"pmids\": [\"14675480\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"WNK1 activates ERK5 through an MEKK2/3-dependent mechanism: WNK1 co-immunoprecipitates with MEKK2 and MEKK3, phosphorylates both in vitro, and WNK1-driven ERK5 activation is blocked by dominant-negative MEKK2/3 or MEK5; siRNA knockdown of WNK1 attenuates EGF-induced ERK5 activation, placing WNK1 upstream of MEKK2/3 in the ERK5 pathway.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative overexpression, in vitro kinase assay, siRNA knockdown\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay plus Co-IP plus epistasis by dominant-negative and siRNA; multiple orthogonal methods\",\n      \"pmids\": [\"14681216\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"Activation of the MEK5-ERK5 pathway causes phosphorylation and stabilization of c-Fos and Fra-1, with the C-terminal half of ERK5 required for maximal transactivation activity of c-Fos and Fra-1; ERK5-mediated phosphorylation of c-Fos occurs at sites distinct from those targeted by ERK1/2.\",\n      \"method\": \"Constitutively active MEK5 expression, phosphorylation mapping, reporter assays\",\n      \"journal\": \"Genes to cells : devoted to molecular & cellular mechanisms\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — phosphorylation site mapping plus functional reporter assays; single lab\",\n      \"pmids\": [\"12622723\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"The full-length MEK5α splice variant, but not MEK5β, activates BMK1/ERK5 and induces nuclear translocation; MEK5β acts as a dominant negative by binding BMK1 and preventing MEK5α association with BMK1, revealing splice variant-dependent control of ERK5 activation.\",\n      \"method\": \"Co-immunoprecipitation, dominant-negative and constitutively active constructs, MEF2 reporter assays, kinase activation assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal Co-IP plus functional reporter assays with mutagenesis; multiple orthogonal approaches\",\n      \"pmids\": [\"14583600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Conditional ablation of BMK1 in adult mice leads to lethality within 2–4 weeks, blood vessel leakage, endothelial cell rounding and apoptosis; in vitro BMK1 removal causes endothelial cell death partly through deregulation of MEF2C, a direct substrate of BMK1; endothelial-specific but not cardiomyocyte-specific deletion recapitulates cardiovascular defects.\",\n      \"method\": \"Mx1-Cre inducible conditional knockout, histology, endothelial cell culture, MEF2C substrate assay\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional genetic deletion with tissue-specific analysis and direct substrate identification (MEF2C); widely cited\",\n      \"pmids\": [\"15085193\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"BMK1/ERK5 is activated via tyrosine 1062 of the RET tyrosine kinase upon GDNF stimulation or MEN2A mutation; this activation requires downstream MEK5 signaling (blocked by dominant-negative MEK5), but not RAS or PI3K pathways; activated BMK1 in turn activates the MEF2C transcription factor.\",\n      \"method\": \"Tyrosine-to-phenylalanine mutagenesis (Y1062F), kinase activity assays, MEK1/PI3K inhibitors, dominant-negative MEK5, MEF2C luciferase reporter\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — site-directed mutagenesis with pharmacological pathway dissection; single lab\",\n      \"pmids\": [\"11237712\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"ERK5 drives LKLF (lung Krüppel-like factor) transcription by activating MEF2 transcription factors through its kinase and transcriptional activation domains; gene profile analysis of erk5-/- embryos and fibroblasts reconstituted with ERK5 or truncated ERK5(1-740, lacking transactivation domain) identified LKLF, flt1, and bnip3 as ERK5 target genes.\",\n      \"method\": \"Gene expression profiling (microarray) in knockout vs. reconstituted cells, shRNA/dominant-negative MEK5, ChIP-like transcription factor assays\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic reconstitution approach with domain deletion and transcription factor analysis; multiple orthogonal methods\",\n      \"pmids\": [\"16166637\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The MEK5-ERK5 pathway is required for neural differentiation in Xenopus embryos: morpholino knockdown of ERK5 or MEK5 reduces head structure and inhibits neural differentiation, while forced activation of MEK5-ERK5 is sufficient to induce neural differentiation; the pathway acts downstream of SoxD and upstream of the proneural gene Xngnr1.\",\n      \"method\": \"Morpholino antisense knockdown, constitutively active MEK5 expression, epistasis analysis in Xenopus embryos\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — morpholino knockdown plus gain-of-function plus epistasis; vertebrate ortholog study consistent with mammalian ERK5 function\",\n      \"pmids\": [\"16179948\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"ERK5 binds to and phosphorylates p90 RSK: ERK5 co-immunoprecipitates with RSK from cell extracts, binds RSK in vitro, and phosphorylates RSK to activate it; the common docking (CD) domain of ERK5 and the D domain of RSK are important for their association; activation of ERK5 weakens its binding to RSK.\",\n      \"method\": \"Co-immunoprecipitation, in vitro binding assay, in vitro kinase assay, domain mutagenesis\",\n      \"journal\": \"Archives of biochemistry and biophysics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — in vitro kinase assay plus Co-IP plus domain mutagenesis; identifies RSK as direct ERK5 substrate\",\n      \"pmids\": [\"16626623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ERK5 activation by PDGF-BB in hepatic stellate cells is Src-dependent; ERK5 silencing inhibits PDGF-BB-induced cell proliferation and c-Jun expression/activation, while ERK5 depletion increases cell migration associated with redistribution of focal contacts and decreased phosphorylation of FAK, paxillin, and PAK.\",\n      \"method\": \"siRNA knockdown, Src inhibitor, migration/proliferation assays, phosphorylation analysis\",\n      \"journal\": \"Journal of hepatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — siRNA knockdown with defined signaling and phenotypic readouts; single lab\",\n      \"pmids\": [\"17998143\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"ERK5 is activated at G2-M and required for timely mitotic entry; ERK5 activates NF-κB through RSK2-mediated phosphorylation and degradation of IκB; NF-κB inhibition at G2-M delays mitotic entry and reduces cyclin B1, cyclin B2, Plk-1, and cdc25B transcription; constitutive ERK5 activation-induced mitosis is blocked by NF-κB inhibition.\",\n      \"method\": \"Cell cycle synchronization, kinase assays, reporter assays, dominant-negative and constitutively active constructs, gene expression analysis\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple epistatic approaches linking ERK5→RSK2→NF-κB→cell cycle genes with genetic rescue experiments\",\n      \"pmids\": [\"17452529\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MEK5-ERK5 pathway mediates fluid shear stress inhibition of TNF-α-induced JNK activation in endothelial cells; selective MEK5 inhibitor BIX02188 completely reversed flow inhibition of TNF-mediated JNK activation, while ERK1/2-selective inhibitor PD184352 had no effect, placing MEK5-ERK5 as the key mediator of atheroprotective flow signaling.\",\n      \"method\": \"Pharmacological inhibitors (BIX02188, PD184352), shear stress apparatus, JNK activity assay, NF-κB reporter\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — selective inhibitor comparison with functional readout; single lab\",\n      \"pmids\": [\"18358237\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"EGF-induced ERK5 activation controls Slug expression in keratinocytes; ectopic Erk5 activation increases Slug mRNA and accelerates wound healing; Erk5 shRNA knockdown reduces keratinocyte motility, Slug induction, and disrupts desmosome organization, establishing an EGFR/Erk5/Slug pathway controlling cytoskeleton organization and cell motility.\",\n      \"method\": \"Erk5 shRNA knockdown, constitutively active Erk5 expression, wound healing assay, migration assay, desmosome analysis\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — shRNA plus gain-of-function with defined pathway and phenotypic readouts; single lab\",\n      \"pmids\": [\"18716062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MEK5-ERK5 pathway regulates apoptosis of developing thymocytes but has no function in positive selection; ERK5 activity correlates with levels of Nur77 family members but not Bim, distinguishing the ERK5 apoptosis pathway from ERK1/2 in T-cell development.\",\n      \"method\": \"Retroviral expression of dominant-negative and constitutively active MEK5, thymocyte apoptosis assays, Nur77/Bim expression analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — bidirectional genetic manipulation with defined downstream gene and phenotypic readout; genetic epistasis established\",\n      \"pmids\": [\"18548009\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Constitutive activation of MEK5/ERK5 signaling inhibits endothelial cell migration and increases focal contact area; this is associated with reduced expression of p130Cas, a key player in directed cell migration, and altered actin organization, demonstrating ERK5 controls endothelial cell migration and morphology.\",\n      \"method\": \"Retroviral gene transfer (constitutively active MEK5), migration assays, focal contact measurement, actin imaging, p130Cas expression analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — gain-of-function with defined molecular mechanism (p130Cas) and multiple phenotypic readouts; single lab\",\n      \"pmids\": [\"19605361\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ERK5 is phosphorylated during mitosis at multiple sites in its C-terminal region by CDK1 (not MEK5); CDK1 co-precipitates with ERK5 in mitotic cells; CDK1 inhibitor RO3306 reverses mitotic ERK5 phosphorylation; this CDK1-dependent phosphorylation inhibits ERK5 activity and regulates its nucleo-cytoplasmic shuttling.\",\n      \"method\": \"Co-immunoprecipitation, CDK1 inhibitor, phosphorylation site mutagenesis, nuclear/cytoplasmic fractionation\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — Co-IP plus mutagenesis plus pharmacological CDK1 inhibition; independently confirmed by a parallel study\",\n      \"pmids\": [\"20736311\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"ERK5 phosphorylation during mitosis occurs at its C-terminal half (not at the TEY activation motif) and is CDK-dependent rather than MEK5-dependent; five mitotic phosphorylation sites were identified; mutagenesis showed these phosphorylations inhibit ERK5 activity and regulate ERK5 nuclear-cytoplasmic shuttling.\",\n      \"method\": \"Mass spectrometry phosphorylation site identification, mutagenesis, CDK inhibitors, fractionation assays\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — MS-based phosphorylation site identification plus mutagenesis plus functional validation; corroborated by independent study\",\n      \"pmids\": [\"20667468\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"BMK1/ERK5 interacts with promyelocytic leukemia protein (PML) and inhibits its tumor-suppressor function through phosphorylation; activated BMK1 inhibits PML-dependent p21 activation; a small-molecule inhibitor XMD8-92 was developed that blocks BMK1 kinase activity and suppresses tumor growth in vivo by 95%.\",\n      \"method\": \"Co-immunoprecipitation, in vitro phosphorylation assay, p21 reporter assay, xenograft tumor model, pharmacological inhibition\",\n      \"journal\": \"Cancer cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — Co-IP plus in vitro phosphorylation plus in vivo tumor suppression with pharmacological inhibitor; multiple orthogonal methods\",\n      \"pmids\": [\"20832753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"X-ray crystal structure of the human ERK5 kinase domain in complex with a selective benzo[e]pyrimido[5,4-b]diazepine-6(11H)-one inhibitor was determined; the structure reveals specific residue differences in the ATP-binding site compared to related ERKs, p38s, and JNKs that allow development of ERK5-specific inhibitors.\",\n      \"method\": \"X-ray crystallography\",\n      \"journal\": \"Journal of medicinal chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — crystal structure determination; provides structural basis for selective inhibitor design\",\n      \"pmids\": [\"23656407\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"ERK5 is degraded through the ubiquitin-proteasome system in a process mediated by the tumor suppressor VHL through a prolyl hydroxylation-dependent mechanism; VHL-negative cell lines have elevated ERK5, and ERK5 knockdown in these cells decreases proliferation and migration.\",\n      \"method\": \"Transfection assays, endogenous ERK5 analysis in VHL-positive and -negative cell lines, proteasome inhibitor experiments, siRNA knockdown\",\n      \"journal\": \"Neoplasia (New York, N.Y.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — VHL-dependent degradation with functional consequence; single lab with multiple cell line systems\",\n      \"pmids\": [\"23730213\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"XIAP directly interacts with MEKK2/3 and competes with PB1 domain-mediated binding to MEK5; XIAP and cIAP1 conjugate predominantly K63-linked ubiquitin chains to MEKK2 and MEKK3, directly impeding MEK5-ERK5 interaction in a trimeric complex and leading to ERK5 inactivation; loss of XIAP or cIAP1 leads to hyperactivation of ERK5.\",\n      \"method\": \"Co-immunoprecipitation, ubiquitination assays, domain competition assays, ubiquitin chain linkage analysis, skeletal myoblast differentiation assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — direct interaction mapping plus K63 ubiquitination characterization plus functional consequence in differentiation; rigorous multi-method study\",\n      \"pmids\": [\"24975362\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"ERK5 activation in macrophages promotes efferocytosis; macrophage-specific ERK5-null mice exhibit reduced efferocytosis and accelerated atherosclerotic plaque formation when crossed with LDL receptor-/- mice on a high-cholesterol diet; statins robustly activate ERK5 in macrophages.\",\n      \"method\": \"Macrophage-specific conditional ERK5 knockout, efferocytosis assays, atherosclerosis model (LDLR-/- mice), pharmacological ERK5 activation\",\n      \"journal\": \"Circulation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — cell-type-specific conditional knockout with in vivo atherosclerosis readout and mechanistic efferocytosis assays\",\n      \"pmids\": [\"25001623\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"IFN-γ-mediated induction of LRRK2 in macrophages is suppressed by pharmacological inhibition and RNA interference of ERK5, establishing ERK5 as a required mediator of the IFN-γ signaling pathway inducing LRRK2 expression.\",\n      \"method\": \"ERK5 pharmacological inhibition, siRNA knockdown, LRRK2 immunostaining, differentiation of THP-1 cells and primary monocytes\",\n      \"journal\": \"Journal of neurochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological and genetic knockdown with defined pathway placement; single lab\",\n      \"pmids\": [\"24479685\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Genetic deletion of ERK1/2 in intestinal epithelial cells results in supraphysiological ERK5 pathway activity; combined pharmacological targeting of MEK1/2 and MEK5 is more effective than single treatment in suppressing proliferation in intestinal organoids and colorectal cancer lines, demonstrating ERK5 provides a bypass proliferative route when ERK1/2 is abrogated.\",\n      \"method\": \"Conditional ERK1/2 knockout mice, MEK1/2 and MEK5/ERK5 pharmacological inhibitors, intestinal organoid culture, CRC cell lines\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic deletion plus pharmacological combination; functional epistasis established in vivo and in organoids\",\n      \"pmids\": [\"27187615\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Selective ERK5 kinase inhibitors have no antiinflammatory or antiproliferative activity, whereas less selective inhibitors block both ERK5 and BET bromodomains; the source of efficacy of previously reported ERK5 inhibitors is off-target activity on bromodomains; phenotypes from genetic deletion of ERK5 likely arise from removal of a noncatalytic function.\",\n      \"method\": \"Synthesis of selective ERK5 inhibitors, bromodomain selectivity profiling (KINOMEscan, BROMOscan), cell proliferation and inflammation assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — rigorous selectivity profiling with functional assays demonstrating kinase-independent function; challenges prior mechanistic interpretations\",\n      \"pmids\": [\"27679845\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"ERK5 maintains embryonic stem cells in the naive pluripotent state and suppresses progression toward primed pluripotency and neuroectoderm differentiation; ERK5 also inhibits a cardiomyocyte-specific differentiation program; these functions were dissected from BRD4 functions using CRISPR/Cas9 ERK5 knockout and compound selectivity engineering.\",\n      \"method\": \"CRISPR/Cas9 knockout, selective ERK5 inhibitor/BET inhibitor comparison, pluripotency state assays, differentiation assays\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — CRISPR/Cas9 with compound selectivity engineering to distinguish ERK5 from BRD4 functions; multiple orthogonal approaches\",\n      \"pmids\": [\"27498864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"YAP promotes myogenic differentiation through the MEK5-ERK5 pathway; YAP activates the Abl/Src/MEKK3/MEK5/ERK5 kinase cascade; co-immunoprecipitation showed YAP interacts with MEKK3 and ERK5; MEKK3 PPGY motif (aa 178-181) mediates interaction with YAP, and Y181F mutation inhibits MEK5/ERK5 activation and myogenesis.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis, constitutive expression, kinase activation assays, myogenic differentiation assays\",\n      \"journal\": \"FASEB journal : official publication of the Federation of American Societies for Experimental Biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP plus mutagenesis plus functional differentiation readout; single lab\",\n      \"pmids\": [\"28356344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Mitochondrial complex I activity induces ERK5 expression through fumarate accumulation; ERK5 in turn induces MEF2-dependent NRF2 expression, activating the antioxidant response; blocking OXPHOS decreases Erk5 and Nrf2 expression in vivo, establishing an OXPHOS-fumarate-ERK5-MEF2-NRF2 axis for antioxidant response.\",\n      \"method\": \"OXPHOS inhibition, fumarate supplementation, MEF2/NRF2 reporter assays, fibroblasts from mitochondrial disorder patients, mouse model\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — metabolic-genetic epistasis with multiple cell and animal models; single lab\",\n      \"pmids\": [\"29743487\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"IFN-γ receptor stimulation activates ULK1, which interacts with and phosphorylates MLK3, leading to downstream ERK5 activation; this ULK1-MLK3-ERK5 axis is required for transcription of antiviral IFN-stimulated genes (ISGs) and IFN-γ-dependent antiviral effects, independent of autophagy.\",\n      \"method\": \"Kinase interaction assays, phosphorylation analysis, antiviral assays, gene expression analysis, pathway inhibition\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ULK1-MLK3 interaction identification plus functional antiviral readout; novel pathway placed by epistasis\",\n      \"pmids\": [\"30459284\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Resistance to ERK1/2 inhibitor SCH772984 in BRAFV600E melanoma cells involves stimulation of the IGF1R-MEK5-ERK5 signaling pathway, which counteracts Erk1/2 inhibition; IGF1R inhibitor linsitinib blocked Erk5 activation in resistant cells, establishing this axis as a resistance bypass route.\",\n      \"method\": \"ERKi-resistant cell line generation, pathway analysis, IGF1R inhibitor treatment, 3D spheroid assays, xenograft models\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — mechanistic pathway identification by resistance profiling with pharmacological epistasis; single lab\",\n      \"pmids\": [\"30833419\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"Small molecule ERK5 kinase inhibitors paradoxically activate ERK5 transcriptional transactivation domain activity by stimulating nuclear localization of ERK5; this kinase domain occupancy-driven nuclear translocation activates the C-terminal transactivation domain independently of kinase activity.\",\n      \"method\": \"ERK5 kinase and transcriptional reporter assays, nuclear localization imaging, selective ERK5 inhibitor panel\",\n      \"journal\": \"Biochemical Society transactions\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — kinase inhibitor-induced paradoxical activation demonstrated by dual readout (kinase vs. transcriptional); mechanistically important finding replicated across multiple inhibitors\",\n      \"pmids\": [\"32915196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Mechanosensitive channel PIEZO1 senses shear force and activates CaMKII, which interacts with and activates MEKK3, promoting MEKK3/MEK5/ERK5 signaling and ultimately inducing KLF2/4 transcription in endothelial cells; endothelial-specific Piezo1 deletion reduces KLF2/4 expression in vivo.\",\n      \"method\": \"Endothelial-specific Piezo1 knockout mice, co-immunoprecipitation (CaMKII-MEKK3), calcium imaging, shear stress experiments, KLF2/4 expression analysis\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic knockout plus Co-IP plus functional pathway placement; single lab\",\n      \"pmids\": [\"35883633\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"ERK5 S496 phosphorylation mediates both senescence-associated secretory phenotype (SASP) and senescence-associated stemness by upregulating AHR in macrophages; S496 phosphorylation induces NRF2 SUMOylation at K518 to inhibit NRF2 transcriptional activity without altering ERK5 catalytic activity; ERK5 S496A knock-in mice are protected from atherosclerosis.\",\n      \"method\": \"CRISPR/Cas9 knock-in (ERK5 S496A), imaging mass cytometry, bone marrow-derived macrophage isolation, RNA-seq, NRF2 SUMOylation assays, atherosclerosis model\",\n      \"journal\": \"Circulation research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — phosphomimetic knock-in mouse plus mechanistic biochemistry (NRF2 SUMOylation) plus in vivo disease model; multiple orthogonal methods\",\n      \"pmids\": [\"37264926\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"BMK1 signaling suppresses epithelial-mesenchymal transition (EMT): BMK1 elevation augments E-cadherin-mediated cell-cell adhesion and reduces mesenchymal markers; BMK1 depletion promotes Snail nuclear accumulation through Akt/GSK3β signaling activated by increased DEPTOR expression (mTOR inhibitor); BMK1 depletion promotes metastasis in vivo.\",\n      \"method\": \"BMK1 overexpression and siRNA knockdown, EMT marker analysis, nuclear/cytoplasmic fractionation, DEPTOR modulation, in vivo metastasis model\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — bidirectional genetic manipulation with mechanistic pathway (DEPTOR/mTOR/Akt/GSK3β/Snail) and in vivo validation; single lab\",\n      \"pmids\": [\"22282661\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"Dichloroacetate (DCA) increases ERK5 expression through fumarate accumulation (OXPHOS induction), which activates the transcription factor MEF2 to drive LDLR transcription and LDL intake; pharmacological or genetic inhibition of the ERK5/MEF2 pathway decreases LDLR expression and LDL uptake.\",\n      \"method\": \"DCA treatment, genetic/pharmacological ERK5/MEF2 inhibition, LDLR luciferase reporter, H3K27 acetylation ChIP, primary hepatocytes, mouse models\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ChIP plus reporter assays plus multiple cell and animal models; mechanistic ERK5→MEF2→LDLR pathway established; single lab\",\n      \"pmids\": [\"28878225\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"ERK5 inhibition or silencing in endometrial cancer impairs NF-κB pathway by downregulating NEMO/IKKγ expression, leading to impaired p65/RELA activity and apoptosis; overexpression of NEMO/IKKγ rescues this apoptosis, placing ERK5 upstream of NEMO in an ERK5-NEMO-NF-κB survival pathway.\",\n      \"method\": \"ERK5 siRNA/pharmacological inhibition, MEK5 genetic deletion, NEMO rescue overexpression, xenograft model, NF-κB reporter, correlation in human EC tumor samples\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — rescue experiment (NEMO overexpression) plus xenograft validation plus human tissue correlation; single lab\",\n      \"pmids\": [\"36123565\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"ERK5 inhibition induces p21-mediated cellular senescence in melanoma: genetic and pharmacological ERK5 blockade increases senescence-associated β-galactosidase activity, p21 expression, and SASP cytokines (CXCL1, CXCL8, CCL20); knockdown of p21 suppresses ERK5 inhibition-induced senescence, identifying p21 as the key mediator; confirmed in vivo in melanoma xenografts.\",\n      \"method\": \"ERK5 shRNA knockdown, XMD8-92 pharmacological inhibition, transcriptomic analysis, senescence assays (β-galactosidase), p21 siRNA rescue, xenograft model\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — bidirectional genetic manipulation plus pharmacology plus transcriptomics plus rescue experiment plus in vivo validation; multiple orthogonal methods\",\n      \"pmids\": [\"34799355\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"MEK5/ERK5 inhibition in macrophages reduces IL-4-induced M2 differentiation (Arg-1, Ym-1, Fizz-1 expression) independently of STAT3/STAT6 phosphorylation, but through decreased c-Myc expression; myeloid-specific Erk5 conditional knockout (LysMcre/Erk5f/f) confirms ERK5 requirement for IL-4-induced M2 polarization.\",\n      \"method\": \"MEK5/ERK5 pharmacological inhibition, myeloid-specific conditional ERK5 knockout, M2 marker analysis, STAT3/STAT6 phosphorylation, c-Myc expression analysis\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — conditional cell-type-specific knockout plus pharmacological confirmation plus mechanistic exclusion (STAT independence); multiple methods\",\n      \"pmids\": [\"32745297\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"MAPK7/ERK5 is a unique MAP kinase activated by the MEK5 kinase (upstream regulated by MEKK2/3, WNK1, and PIEZO1-CaMKII) that contains both an N-terminal kinase domain (activated by MEK5-mediated dual TEY phosphorylation) and a C-terminal transcriptional activation domain that directly coactivates MEF2 transcription factors to drive target gene expression (including KLF2, LKLF, NRF2, and c-Jun); during mitosis, CDK1 phosphorylates ERK5 at multiple C-terminal sites independently of MEK5 to regulate ERK5 nucleo-cytoplasmic shuttling and suppress its activity; ERK5 phosphorylates direct substrates including MEF2C, PML (inhibiting its tumor suppressor function), and RSK (activating it through its CD domain interaction), and is inactivated by XIAP/cIAP1-mediated K63-linked ubiquitination of MEKK2/3; physiologically, ERK5 signaling is essential for cardiovascular development, endothelial cell survival and vascular integrity, retrograde neurotrophin signaling, and immune cell differentiation (macrophage efferocytosis, M2 polarization, thymocyte apoptosis), while paradoxically, selective kinase inhibitors activate ERK5's transcriptional domain through nuclear translocation, indicating that many biological functions attributed to ERK5 arise from its non-catalytic transcriptional activity rather than kinase activity alone.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"MAPK7 (ERK5/BMK1) is an atypical MAP kinase that integrates mitogenic, mechanical, and stress signals to regulate cardiovascular development, immune cell function, cell proliferation, and differentiation through both catalytic and non-catalytic mechanisms. Activated by MEK5-mediated dual TEY phosphorylation downstream of MEKK2/3 (itself regulated by WNK1, PIEZO1-CaMKII, and XIAP/cIAP1-mediated K63 ubiquitination), ERK5 phosphorylates substrates including MEF2C, PML, and RSK, and uniquely possesses a C-terminal transcriptional activation domain that directly coactivates MEF2 transcription factors to drive expression of KLF2, NRF2, LKLF, and c-Jun [PMID:11046135, PMID:16166637, PMID:20832753, PMID:16626623, PMID:14681216]. During mitosis, CDK1 phosphorylates ERK5 at C-terminal sites independently of MEK5, inhibiting its activity and regulating nucleo-cytoplasmic shuttling, while selective kinase inhibitors paradoxically activate ERK5's transcriptional domain through forced nuclear translocation, demonstrating that many biological functions attributed to ERK5—including roles in endothelial survival, embryonic vascular development, macrophage efferocytosis, M2 polarization, and stem cell pluripotency—arise substantially from its non-catalytic transcriptional activity [PMID:20736311, PMID:27679845, PMID:32915196, PMID:12093914, PMID:25001623, PMID:27498864]. ERK5 S496 phosphorylation drives senescence-associated phenotypes in macrophages via NRF2 SUMOylation and AHR upregulation, and knock-in mice bearing an S496A mutation are protected from atherosclerosis [PMID:37264926].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Identification of ERK5/BMK1 as a structurally distinct MAP kinase with a unique C-terminal extension established that an additional mammalian MAPK cascade existed beyond ERK1/2, JNK, and p38.\",\n      \"evidence\": \"cDNA cloning and primary structure analysis revealing 816-aa protein with TEY motif and distinctive loop-12/C-terminal domain\",\n      \"pmids\": [\"7646528\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No activating kinase or physiological stimulus identified\", \"Function of C-terminal extension unknown\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Demonstration that MEK5 activates ERK5 in response to EGF independently of Ras, and that dominant-negative ERK5 blocks EGF-induced proliferation, established ERK5 as a functionally distinct MAPK cascade required for mitogenic signaling.\",\n      \"evidence\": \"Dominant-negative ERK5 overexpression blocking EGF-induced S-phase entry; kinase activity assays in multiple cell types\",\n      \"pmids\": [\"9790194\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream kinases activating MEK5 not identified\", \"Direct substrates of ERK5 unknown\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Discovery that ERK5's C-terminal region contains an intrinsic transcriptional activation domain and directly coactivates MEF2 transcription factors revealed a dual kinase/transcription factor architecture unique among MAP kinases.\",\n      \"evidence\": \"Yeast two-hybrid screen with MEF2D MADS domain as bait; domain deletion and luciferase reporter assays confirming coactivation\",\n      \"pmids\": [\"11046135\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether transcriptional activation requires kinase activity not resolved\", \"Target genes of ERK5-MEF2 axis not identified\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"ERK5 was placed in retrograde neurotrophin signaling (Trk→ERK5→CREB→survival) and downstream of RET/GDNF via MEK5, broadening its receptor inputs and establishing a specific role in neuronal survival distinct from ERK1/2.\",\n      \"evidence\": \"Compartmentalized neuron cultures with dominant-negative ERK5 blocking retrograde survival; RET Y1062F mutagenesis abolishing ERK5 activation\",\n      \"pmids\": [\"11544482\", \"11237712\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation of CREB by ERK5 not demonstrated\", \"Whether ERK5 transcriptional domain contributes to neuronal survival unknown\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"ERK5 knockout mice dying at E9.5–10.5 with severe cardiovascular defects established ERK5 as essential for vascular development and cardiac morphogenesis in vivo.\",\n      \"evidence\": \"Constitutive Erk5 gene knockout in mice with histological analysis showing endothelial disorganization and vascular remodeling failure\",\n      \"pmids\": [\"12093914\", \"14675480\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cell-type-specific contributions (endothelial vs. cardiomyocyte) not resolved by constitutive knockout\", \"Whether kinase activity or transcriptional domain mediates developmental function unknown\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identification of WNK1→MEKK2/3→MEK5 as the upstream kinase cascade and MEK5α/β splice variant regulation defined the complete four-tier kinase module activating ERK5.\",\n      \"evidence\": \"Co-IP of WNK1 with MEKK2/3, in vitro phosphorylation, siRNA knockdown of WNK1 reducing EGF-induced ERK5 activation; MEK5α vs. MEK5β differential binding to ERK5\",\n      \"pmids\": [\"14681216\", \"14583600\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological contexts where WNK1 is the dominant ERK5 activator not defined\", \"How MEK5 splice variant ratio is regulated unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Conditional ERK5 deletion in adult mice causing endothelial apoptosis, blood vessel leakage, and lethality within weeks—with MEF2C identified as a direct substrate—demonstrated that ERK5 is continuously required for adult vascular integrity through MEF2C phosphorylation.\",\n      \"evidence\": \"Mx1-Cre inducible conditional knockout; endothelial-specific deletion recapitulating phenotype; in vitro MEF2C substrate assay\",\n      \"pmids\": [\"15085193\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full spectrum of MEF2C target genes downstream of ERK5 in endothelium not mapped\", \"Relative contribution of kinase vs. transcriptional domain to endothelial survival not resolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Identification of LKLF/KLF2 as a direct transcriptional target of ERK5-MEF2 axis (requiring both kinase and C-terminal transactivation domains) established the key downstream effector genes mediating ERK5 vascular and anti-inflammatory functions.\",\n      \"evidence\": \"Gene expression profiling of erk5−/− embryos reconstituted with full-length vs. C-terminally truncated ERK5\",\n      \"pmids\": [\"16166637\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"ChIP evidence for direct MEF2 occupancy at LKLF promoter not shown\", \"Whether LKLF alone accounts for vascular phenotype not tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"ERK5 was shown to directly phosphorylate and activate RSK through CD domain–D domain interaction, and to promote NF-κB activation via RSK2-mediated IκB degradation at G2-M, connecting ERK5 to cell cycle progression and NF-κB signaling.\",\n      \"evidence\": \"In vitro kinase assay, Co-IP, domain mutagenesis for ERK5-RSK; cell cycle synchronization linking ERK5→RSK2→NF-κB→cyclin B1 transcription\",\n      \"pmids\": [\"16626623\", \"17452529\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether RSK is a major physiological ERK5 substrate in vivo not established\", \"NF-κB dependence observed in one cell system\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"ERK5 was placed in atheroprotective shear stress signaling (MEK5-ERK5 mediating flow-dependent JNK suppression) and in thymocyte apoptosis regulation via Nur77, extending ERK5 functions to mechanosensing and immune cell development.\",\n      \"evidence\": \"Selective MEK5 inhibitor BIX02188 in endothelial shear stress assay; dominant-negative/constitutively active MEK5 in thymocyte apoptosis with Nur77 expression analysis\",\n      \"pmids\": [\"18358237\", \"18548009\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanosensor upstream of MEK5-ERK5 in shear stress not identified at this point\", \"Whether ERK5 directly phosphorylates Nur77 not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Discovery that CDK1 phosphorylates ERK5 at multiple C-terminal sites during mitosis—independently of MEK5—to inhibit ERK5 and regulate its nuclear-cytoplasmic shuttling revealed a non-canonical regulation mechanism decoupling mitotic ERK5 phosphorylation from its activation.\",\n      \"evidence\": \"Mass spectrometry identification of five mitotic phosphorylation sites; CDK1 Co-IP with ERK5; CDK1 inhibitor RO3306 reversing phosphorylation; mutagenesis validating functional consequences\",\n      \"pmids\": [\"20736311\", \"20667468\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of CDK1-mediated ERK5 inhibition during mitosis not fully defined\", \"Whether CDK1 phosphorylation affects C-terminal transcriptional domain directly not tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identification of PML as a direct ERK5 substrate whose tumor-suppressor function (p21 induction) is inhibited by ERK5 phosphorylation provided a direct oncogenic mechanism, validated by the ERK5 inhibitor XMD8-92 suppressing tumor growth in vivo.\",\n      \"evidence\": \"Co-IP of ERK5 with PML, in vitro phosphorylation, p21 reporter suppression, xenograft tumor model with 95% growth suppression by XMD8-92\",\n      \"pmids\": [\"20832753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PML phosphorylation sites by ERK5 not mapped\", \"XMD8-92 selectivity later questioned (bromodomain off-targets)\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"XIAP and cIAP1 were identified as negative regulators of ERK5 signaling through K63-linked ubiquitination of MEKK2/3, which disrupts the MEKK2/3-MEK5 interaction, revealing a ubiquitin-dependent mechanism that restrains ERK5 pathway activation.\",\n      \"evidence\": \"Co-IP, K63-linked ubiquitin chain analysis, PB1 domain competition assays, skeletal myoblast differentiation readout\",\n      \"pmids\": [\"24975362\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological triggers that relieve XIAP/cIAP1-mediated suppression not identified\", \"Whether K63 ubiquitination also affects MEKK2/3 stability not tested\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Macrophage-specific ERK5 deletion revealed ERK5 is required for efferocytosis and protection from atherosclerosis, while ERK5 also mediates IFN-γ-induced LRRK2 expression, establishing ERK5 as a central node in macrophage immune function.\",\n      \"evidence\": \"Macrophage-specific conditional ERK5 knockout crossed to LDLR−/− mice; efferocytosis assays; ERK5 siRNA and inhibitor reducing LRRK2 induction\",\n      \"pmids\": [\"25001623\", \"24479685\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct ERK5 substrates mediating efferocytosis not identified\", \"Whether kinase activity or transcriptional domain required for macrophage functions not distinguished\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"The landmark finding that selective ERK5 kinase inhibitors lack antiproliferative or anti-inflammatory activity—and that prior inhibitor efficacy derived from off-target bromodomain inhibition—established that ERK5's major biological functions depend on its non-catalytic transcriptional domain rather than kinase activity alone.\",\n      \"evidence\": \"Synthesis of highly selective ERK5 inhibitors; KINOMEscan and BROMOscan profiling demonstrating bromodomain cross-reactivity of XMD8-92 and BIX02189; functional assays showing no effect of selective kinase inhibition\",\n      \"pmids\": [\"27679845\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether any ERK5 kinase substrates are physiologically relevant remains uncertain\", \"Mechanism by which kinase domain occupancy affects C-terminal domain not resolved\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"ERK5 maintains naive pluripotency in embryonic stem cells and suppresses neuroectoderm/cardiomyocyte differentiation, with CRISPR knockout distinguishing ERK5-specific from BRD4-dependent functions; concurrently, ERK5 was shown to serve as a bypass proliferative route when ERK1/2 is deleted in intestinal epithelium.\",\n      \"evidence\": \"CRISPR/Cas9 ERK5 knockout in ESCs with selective compound comparison; conditional ERK1/2 knockout in intestinal epithelium with MEK5 inhibitor combination in organoids and CRC lines\",\n      \"pmids\": [\"27498864\", \"27187615\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Transcriptional targets of ERK5 in pluripotency maintenance not defined\", \"Whether ERK5 bypass in ERK1/2-null cells requires kinase activity not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"The paradox that ERK5 kinase inhibitors activate ERK5's transcriptional domain by promoting nuclear translocation explained why kinase inhibition fails to recapitulate genetic deletion phenotypes, fundamentally reframing therapeutic targeting strategies for ERK5.\",\n      \"evidence\": \"Panel of selective ERK5 inhibitors tested with dual kinase activity and transcriptional reporter assays; nuclear localization imaging\",\n      \"pmids\": [\"32915196\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural mechanism linking kinase domain occupancy to conformational change enabling nuclear import not resolved\", \"Whether degrader approaches can overcome paradoxical activation not tested\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"ERK5 was shown to be required for IL-4-induced M2 macrophage polarization through c-Myc (independently of STAT3/STAT6), expanding its immune functions beyond efferocytosis to alternative macrophage activation.\",\n      \"evidence\": \"Myeloid-specific conditional ERK5 knockout (LysMcre/Erk5f/f) plus MEK5/ERK5 pharmacological inhibition; M2 marker and c-Myc expression analysis\",\n      \"pmids\": [\"32745297\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether ERK5 directly regulates c-Myc transcription or stability not resolved\", \"In vivo consequence of ERK5-dependent M2 polarization defect not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"PIEZO1 was identified as the mechanosensor upstream of ERK5 in endothelial shear stress signaling, activating CaMKII which directly interacts with MEKK3 to drive MEKK3/MEK5/ERK5-dependent KLF2/4 transcription, completing the mechanotransduction pathway from membrane to nucleus.\",\n      \"evidence\": \"Endothelial-specific Piezo1 knockout mice; CaMKII-MEKK3 Co-IP; calcium imaging; shear stress experiments measuring KLF2/4\",\n      \"pmids\": [\"35883633\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"CaMKII phosphorylation site on MEKK3 not mapped\", \"Whether PIEZO1-ERK5 axis operates in non-endothelial mechanosensing contexts unknown\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"ERK5 S496 phosphorylation was identified as a switch controlling senescence-associated secretory phenotype and stemness in macrophages by inducing NRF2 SUMOylation at K518, with S496A knock-in mice protected from atherosclerosis, providing the first phosphosite-specific in vivo ERK5 disease mechanism.\",\n      \"evidence\": \"CRISPR/Cas9 S496A knock-in mice; imaging mass cytometry; NRF2 SUMOylation assays; atherosclerosis model\",\n      \"pmids\": [\"37264926\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Kinase responsible for S496 phosphorylation not identified\", \"Whether S496 phosphorylation affects ERK5 transcriptional domain function not tested\", \"Generalizability of S496-NRF2 SUMOylation axis beyond macrophages unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The central unresolved question is how to therapeutically target ERK5 given that kinase inhibition paradoxically activates its transcriptional domain; additionally, the structural basis for how kinase domain occupancy triggers conformational opening and nuclear translocation, the relative contributions of kinase versus transcriptional functions across different tissues, and the identity of the kinase that phosphorylates ERK5 at S496 remain unknown.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural mechanism coupling kinase domain occupancy to C-terminal conformational change and nuclear import not determined\", \"No ERK5-selective degrader or dual kinase/transcription-domain inhibitor reported\", \"Kinase phosphorylating S496 unknown\", \"Comprehensive in vivo substrate repertoire for ERK5 kinase activity not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [1, 10, 14, 23]},\n      {\"term_id\": \"GO:0140110\", \"supporting_discovery_ids\": [2, 12, 36]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 14, 23]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [3, 9, 21, 36]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [21, 22]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 7, 9, 26, 37]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [5, 6, 13]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [16, 21, 22]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [10, 19]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [19, 27, 43]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 12, 36]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"MEK5\",\n      \"MEKK2\",\n      \"MEKK3\",\n      \"MEF2C\",\n      \"MEF2D\",\n      \"PML\",\n      \"RPS6KA1\",\n      \"CDK1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}