{"gene":"RPS6KA4","run_date":"2026-04-28T20:42:06","timeline":{"discoveries":[{"year":1998,"finding":"RPS6KA4 (RSK-B/MSK2) was identified as a substrate of p38α MAPK via an intracellular interaction screen; it is activated by p38αMAPK and more weakly by ERK1, contains two catalytic domains (N-terminal PKC-like and C-terminal CaM kinase-like), phosphorylates CREB and c-Fos peptides, drives CRE- and AP1-dependent reporter expression, and localizes to the cell nucleus where it co-translocates p38αMAPK.","method":"p38αMAPK-baited intracellular interaction screen, in vitro kinase assay, reporter gene assay, subcellular localization","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (interaction screen, in vitro kinase assay, reporter assay, localization) in single foundational paper","pmids":["9792677"],"is_preprint":false},{"year":2003,"finding":"MSK1 and MSK2 are the major kinases responsible for mitogen- and stress-induced phosphorylation of histone H3 (Ser10, Ser28) and HMG-14 in fibroblasts; this was established using MSK1/MSK2 double-knockout mice showing severely reduced or abolished H3 and HMG-14 phosphorylation, while H3 acetylation remained unimpaired.","method":"MSK1/MSK2 double-knockout mouse fibroblasts, in vivo phosphorylation assay, immediate-early gene induction assay","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with specific phosphorylation readout, replicated across stimuli, highly cited foundational study","pmids":["12773393"],"is_preprint":false},{"year":2002,"finding":"MSK1 and MSK2 are required for stress-induced (and partially mitogen-induced) phosphorylation of transcription factors CREB (Ser133) and ATF1 in primary embryonic fibroblasts, and MSK1/MSK2 double knockout reduces c-fos and junB transcription by ~50% in response to stress stimuli.","method":"MSK1/MSK2 single and double knockout mouse embryonic fibroblasts, phosphorylation assay, gene expression analysis","journal":"Molecular and cellular biology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO with specific biochemical and transcriptional readouts, replicated across multiple stimuli","pmids":["11909979"],"is_preprint":false},{"year":2008,"finding":"MSK1 and MSK2 act as negative regulators of TLR signaling by inducing transcription of DUSP1 and IL-10; they mediate phosphorylation of CREB and ATF1, enabling binding to the promoters of IL-10 and DUSP1 genes. MSK1/2 double-deficient mice show hypersensitivity to LPS-induced endotoxic shock and prolonged contact eczema.","method":"MSK1/MSK2 double-knockout mice, macrophage stimulation with LPS, chromatin immunoprecipitation (ChIP), cytokine measurement, in vivo endotoxin shock model","journal":"Nature immunology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO combined with ChIP and in vivo model, multiple orthogonal methods, highly cited","pmids":["18690222"],"is_preprint":false},{"year":2006,"finding":"MSK1 and MSK2 are required for EGF-induced, but not TNF-induced, histone H3 Ser10 phosphorylation globally and at specific promoters (c-fos, IκBα), and are required for optimal EGF-induced c-fos transcription through control of both H3-Ser10 and CREB phosphorylation.","method":"MSK1/MSK2 knockdown, ChIP, in vivo phosphorylation assay, gene expression analysis","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 — KD with specific phosphorylation and transcriptional readouts, single lab","pmids":["16517600"],"is_preprint":false},{"year":2009,"finding":"CK2 protein kinase physically interacts with MSK2 (but not MSK1) and phosphorylates MSK2 at Ser324; CK2 inhibition or the S324A mutation impairs UV-induced MSK2 kinase activation. MSK2 (but not MSK1) is responsible for UV-induced phosphorylation of NF-κB p65 at Ser276, promoting NF-κB-responsive gene expression.","method":"Co-immunoprecipitation, site-directed mutagenesis (S324A), RNAi knockdown, ectopic expression rescue, in vivo phosphorylation assay, reporter gene assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — Co-IP, mutagenesis, RNAi rescue, multiple orthogonal methods establishing differential regulation and substrate","pmids":["19933278"],"is_preprint":false},{"year":2009,"finding":"MSK2 inhibits p53 transcriptional activity in the absence of stress independently of its kinase activity and upstream MAPK signaling; MSK2 interacts with and inhibits the p53 coactivator p300, associates with the Noxa promoter, and apoptotic stimuli promote MSK2 degradation to relieve p53 inhibition.","method":"Co-immunoprecipitation, kinase-dead mutant analysis, ChIP, gene expression analysis, apoptosis assay","journal":"Science signaling","confidence":"Medium","confidence_rationale":"Tier 2 — Co-IP and ChIP with kinase-dead mutant, mechanistically detailed, single lab","pmids":["19797274"],"is_preprint":false},{"year":2011,"finding":"MSK2 binds PKR and stimulates PKR phosphorylation in the context of HCV replication, apparently functioning as an adaptor independently of its own catalytic activity; MSK1 and RSK2 do not have this effect.","method":"Co-immunoprecipitation, in vivo phosphorylation assay, kinase-dead mutant analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2-3 — Co-IP and kinase-dead mutant, single lab, single paper","pmids":["21385567"],"is_preprint":false},{"year":2013,"finding":"MSK1 and MSK2 regulate cox-2 mRNA stability via an IL-10 feedback mechanism: MSKs promote IL-10 production, which in turn promotes cox-2 mRNA degradation via p38/MK2 and the mRNA-binding protein TTP; MSK1/2 KO macrophages show elevated prostaglandin E2 and cox-2 protein due to reduced IL-10 and impaired mRNA degradation.","method":"MSK1/MSK2 knockout macrophages, IL-10 neutralization, mRNA stability assay, prostaglandin measurement, in vivo LPS model","journal":"Molecular and cellular biology","confidence":"Medium","confidence_rationale":"Tier 2 — genetic KO with pathway dissection, multiple readouts, single lab","pmids":["23382072"],"is_preprint":false},{"year":2013,"finding":"NF-κB plays a crucial role in RPS6KA4 gene expression: TNFα induces RPS6KA4 mRNA via NF-κB, and this is blocked by the NF-κB inhibitor BAY11-7082 or dominant-negative NF-κB; RPS6KA4 in turn inhibits p53 function, and its knockdown enhances α-lipoic acid-induced apoptosis in a p53-dependent manner.","method":"NF-κB inhibitor, dominant-negative NF-κB transfection, RPS6KA4 knockdown and restoration, apoptosis assay, microarray","journal":"Anti-cancer drugs","confidence":"Medium","confidence_rationale":"Tier 2-3 — pharmacological and genetic inhibition with p53-dependent readout, single lab","pmids":["23599020"],"is_preprint":false},{"year":2014,"finding":"MSK1 and MSK2 are the major CREB kinases in LPA-stimulated human fibroblast-like synoviocytes; both MSK1 and MSK2 mediate LPA-induced phosphorylation of CREB at Ser133 downstream of ERK1/2 and p38 MAPK, contributing to IL-8 and MCP-1 secretion.","method":"siRNA silencing of MSK1/MSK2, pharmacological inhibitor SB747651A, shRNA knockdown of CREB1, phosphorylation assay, cytokine measurement","journal":"Biochemical pharmacology","confidence":"Medium","confidence_rationale":"Tier 2-3 — siRNA/shRNA with specific biochemical and secretion readouts, single lab","pmids":["24792438"],"is_preprint":false},{"year":2016,"finding":"miR-93 targets Msk2 (RPS6KA4) in podocytes; Msk2 phosphorylates histone H3 at Ser10 (H3S10), and miR-93-mediated suppression of Msk2 reduces H3S10 phosphorylation and nucleosomal dynamics, thereby ameliorating diabetic nephropathy-associated chromatin remodeling.","method":"Inducible transgenic miR-93 overexpression in podocytes, MSK2 knockdown, H3S10 phosphorylation assay, chromatin remodeling assay, mouse model of diabetic nephropathy","journal":"Nature communications","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo transgenic model with specific substrate readout, single lab","pmids":["27350436"],"is_preprint":false},{"year":2019,"finding":"MSK2 promotes cervical cancer cell proliferation via phosphorylation of PAX8, which leads to suppression of RB phosphorylation and downstream activation of E2F1 and cyclin A2; MSK2 knockdown inhibited PAX8 phosphorylation, reduced E2F1 and cyclin A2 expression, and suppressed proliferation and tumor formation.","method":"MSK2 knockdown, western blot for PAX8/RB/E2F1/cyclin A2 phosphorylation, proliferation and tumor formation assays in vivo and in vitro","journal":"Journal of cellular biochemistry","confidence":"Low","confidence_rationale":"Tier 3 — KD with pathway readout but no direct phosphorylation site mapping, single lab","pmids":["30756420"],"is_preprint":false}],"current_model":"RPS6KA4 (MSK2) is a nuclear serine/threonine kinase activated downstream of ERK1/2 and p38 MAPK (and phosphorylated by CK2 at Ser324 during UV stress) that phosphorylates histone H3 (Ser10/Ser28), HMG-14, CREB (Ser133), ATF1, NF-κB p65 (Ser276), and PAX8 to regulate immediate-early gene transcription, inflammatory cytokine production (including IL-10 and DUSP1 as negative feedback on TLR signaling), and chromatin remodeling; in the absence of stress it also non-catalytically inhibits p53 by interacting with the coactivator p300, and can act as an adaptor to stimulate PKR activation."},"narrative":{"teleology":[{"year":1998,"claim":"Identification of MSK2 as a p38α MAPK substrate established it as a dual-kinase-domain nuclear kinase that phosphorylates CREB and activates CRE/AP1-dependent transcription, answering how p38 signaling reaches nuclear transcription-factor targets.","evidence":"Intracellular interaction screen baited with p38α, in vitro kinase assay, reporter assays, and subcellular fractionation in mammalian cells","pmids":["9792677"],"confidence":"High","gaps":["Physiological substrates beyond CREB peptides not yet defined","Relative contribution of ERK versus p38 axis unclear","No loss-of-function data"]},{"year":2002,"claim":"Genetic knockout demonstrated that MSK1/MSK2 are required for stress-induced CREB and ATF1 phosphorylation and for full immediate-early gene (c-fos, junB) induction, resolving which kinases are the physiological CREB Ser133 kinases downstream of MAPK cascades.","evidence":"MSK1/MSK2 single and double knockout mouse embryonic fibroblasts with phosphorylation and transcription readouts","pmids":["11909979"],"confidence":"High","gaps":["Individual contributions of MSK1 versus MSK2 not fully separated","Stimulus-specific roles (mitogen vs. stress) not delineated for all targets"]},{"year":2003,"claim":"Double-knockout studies established MSK1/MSK2 as the major histone H3 Ser10/Ser28 and HMG-14 kinases in mitogen- and stress-stimulated fibroblasts, linking MAPK signaling directly to chromatin remodeling.","evidence":"MSK1/MSK2 double-knockout mouse fibroblasts with in vivo histone phosphorylation assays across multiple stimuli","pmids":["12773393"],"confidence":"High","gaps":["Locus-specific versus global H3 phosphorylation roles not resolved","Functional consequence of H3 phosphorylation on gene transcription not directly tested"]},{"year":2006,"claim":"ChIP-based promoter analysis showed that MSK1/MSK2 mediate EGF-induced H3 Ser10 phosphorylation at specific gene promoters (c-fos, IκBα) and are required for optimal c-fos transcription, demonstrating locus-specific chromatin kinase function.","evidence":"MSK1/MSK2 knockdown with ChIP and gene expression analysis in stimulated cells","pmids":["16517600"],"confidence":"Medium","gaps":["TNF-induced H3 phosphorylation uses a different kinase — identity unknown","Genome-wide target promoter landscape not mapped"]},{"year":2008,"claim":"In vivo knockout studies revealed that MSK1/MSK2 serve as critical anti-inflammatory effectors by inducing IL-10 and DUSP1 via CREB/ATF1 phosphorylation, establishing a negative-feedback loop on TLR signaling that limits endotoxic shock and contact eczema.","evidence":"MSK1/MSK2 double-knockout mice, macrophage LPS stimulation, ChIP on IL-10 and DUSP1 promoters, in vivo endotoxin shock and eczema models","pmids":["18690222"],"confidence":"High","gaps":["Relative individual contributions of MSK1 versus MSK2 to IL-10 induction not separated","Downstream transcriptional programs beyond IL-10/DUSP1 not profiled"]},{"year":2009,"claim":"Two parallel discoveries established MSK2-specific functions: CK2 phosphorylates MSK2 at Ser324 to enable UV-induced NF-κB p65 Ser276 phosphorylation (distinguishing MSK2 from MSK1), and MSK2 inhibits p53 independently of kinase activity by blocking p300 coactivator function, revealing a non-catalytic adaptor role.","evidence":"Co-IP, S324A mutagenesis, RNAi rescue for CK2–NF-κB axis; Co-IP, kinase-dead mutant, ChIP at Noxa promoter for p53–p300 axis","pmids":["19933278","19797274"],"confidence":"High","gaps":["Structural basis of MSK2–p300 interaction unknown","Whether CK2-dependent activation of MSK2 extends beyond UV stress untested","In vivo relevance of p53 inhibition not confirmed with knockout"]},{"year":2011,"claim":"MSK2 was found to stimulate PKR phosphorylation during HCV replication as an adaptor, independent of its own kinase activity, extending the non-catalytic adaptor paradigm to antiviral signaling.","evidence":"Co-immunoprecipitation and kinase-dead mutant analysis in HCV-replicating cells","pmids":["21385567"],"confidence":"Medium","gaps":["Mechanism by which MSK2 binding activates PKR not defined","Not independently confirmed by another group","In vivo relevance during viral infection untested"]},{"year":2013,"claim":"The MSK-IL-10 axis was extended to post-transcriptional control: MSK1/2-driven IL-10 promotes cox-2 mRNA degradation via p38/MK2/TTP, explaining elevated prostaglandin E2 in MSK-deficient macrophages and broadening the anti-inflammatory reach of MSKs. Separately, NF-κB was shown to transcriptionally induce RPS6KA4 itself, creating a feedforward loop coupling NF-κB activation to p53 suppression.","evidence":"MSK1/2 KO macrophages with mRNA stability and prostaglandin assays; NF-κB inhibitor and dominant-negative experiments with MSK2 knockdown/rescue and apoptosis assays","pmids":["23382072","23599020"],"confidence":"Medium","gaps":["Direct NF-κB binding sites in the RPS6KA4 promoter not mapped","Relative roles of MSK1 versus MSK2 in cox-2 mRNA regulation unclear"]},{"year":2016,"claim":"miR-93 was identified as a physiological suppressor of MSK2 in podocytes, linking MSK2-driven H3 Ser10 phosphorylation and chromatin dynamics to diabetic nephropathy pathogenesis.","evidence":"Inducible miR-93 transgenic mice, MSK2 knockdown in podocytes, H3S10 phosphorylation and chromatin remodeling assays, diabetic nephropathy model","pmids":["27350436"],"confidence":"Medium","gaps":["Target genes affected by MSK2-driven H3S10 phosphorylation in podocytes not identified","Whether MSK1 compensates in podocytes not addressed"]},{"year":null,"claim":"Key unresolved questions include: the genome-wide set of MSK2-specific (versus MSK1-redundant) chromatin and transcription-factor targets; the structural basis of MSK2's non-catalytic interactions with p300 and PKR; and whether MSK2-selective functions identified in vitro (NF-κB p65 phosphorylation, p53 inhibition, PKR activation) are recapitulated with MSK2 single-knockout models in vivo.","evidence":"","pmids":[],"confidence":"High","gaps":["No MSK2 single-knockout phenotype characterized in vivo for p53/NF-κB/PKR axes","No structural model of MSK2–p300 or MSK2–PKR complexes","Genome-wide MSK2-specific ChIP-seq targets not available"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,2,4,5,10,11]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,1,2,5]},{"term_id":"GO:0042393","term_label":"histone binding","supporting_discovery_ids":[1,4,11]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[6,7]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[6,9]}],"localization":[{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[0,4,6]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,5,9]},{"term_id":"R-HSA-4839726","term_label":"Chromatin organization","supporting_discovery_ids":[1,4,11]},{"term_id":"R-HSA-74160","term_label":"Gene expression (Transcription)","supporting_discovery_ids":[2,3,4]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[3,8]},{"term_id":"R-HSA-5357801","term_label":"Programmed Cell Death","supporting_discovery_ids":[6,9]}],"complexes":[],"partners":["MAPK14","CREB1","ATF1","RELA","CSNK2A1","EP300","EIF2AK2"],"other_free_text":[]},"mechanistic_narrative":"RPS6KA4 (MSK2) is a dual-kinase-domain nuclear serine/threonine kinase activated downstream of both ERK1/2 and p38 MAPK that functions as a central chromatin and transcription-factor kinase linking mitogen and stress signaling to immediate-early gene expression, inflammatory cytokine regulation, and chromatin remodeling. MSK2, together with the paralog MSK1, is the major kinase responsible for stimulus-induced phosphorylation of histone H3 at Ser10 and Ser28, HMG-14, and the transcription factors CREB (Ser133) and ATF1, thereby driving transcription of c-fos, junB, IL-10, and DUSP1; loss of both MSKs causes hypersensitivity to endotoxic shock owing to defective IL-10-mediated negative feedback on TLR signaling [PMID:12773393, PMID:11909979, PMID:18690222]. MSK2 is selectively phosphorylated by CK2 at Ser324 during UV stress, enabling it to phosphorylate NF-κB p65 at Ser276 and activate NF-κB-dependent gene expression, a function not shared by MSK1 [PMID:19933278]. Independent of its catalytic activity, MSK2 inhibits p53 transcriptional function by sequestering the coactivator p300 at target promoters such as Noxa; apoptotic stimuli relieve this inhibition through MSK2 degradation [PMID:19797274]."},"prefetch_data":{"uniprot":{"accession":"O75676","full_name":"Ribosomal protein S6 kinase alpha-4","aliases":["90 kDa ribosomal protein S6 kinase 4","Nuclear mitogen- and stress-activated protein kinase 2","Ribosomal protein kinase B","RSKB"],"length_aa":772,"mass_kda":85.6,"function":"Serine/threonine-protein kinase that is required for the mitogen or stress-induced phosphorylation of the transcription factors CREB1 and ATF1 and for the regulation of the transcription factor RELA, and that contributes to gene activation by histone phosphorylation and functions in the regulation of inflammatory genes. Phosphorylates CREB1 and ATF1 in response to mitogenic or stress stimuli such as UV-C irradiation, epidermal growth factor (EGF) and anisomycin. Plays an essential role in the control of RELA transcriptional activity in response to TNF. Phosphorylates 'Ser-10' of histone H3 in response to mitogenics, stress stimuli and EGF, which results in the transcriptional activation of several immediate early genes, including proto-oncogenes c-fos/FOS and c-jun/JUN. May also phosphorylate 'Ser-28' of histone H3. Mediates the mitogen- and stress-induced phosphorylation of high mobility group protein 1 (HMGN1/HMG14). In lipopolysaccharide-stimulated primary macrophages, acts downstream of the Toll-like receptor TLR4 to limit the production of pro-inflammatory cytokines. Functions probably by inducing transcription of the MAP kinase phosphatase DUSP1 and the anti-inflammatory cytokine interleukin 10 (IL10), via CREB1 and ATF1 transcription factors","subcellular_location":"Nucleus","url":"https://www.uniprot.org/uniprotkb/O75676/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/RPS6KA4","classification":"Not Classified","n_dependent_lines":13,"n_total_lines":1208,"dependency_fraction":0.01076158940397351},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000162302","cell_line_id":"CID001264","localizations":[{"compartment":"nucleoplasm","grade":3}],"interactors":[{"gene":"HIST2H2AA3;HIST2H2AC;H2AFJ","stoichiometry":0.2},{"gene":"RPS6KA1","stoichiometry":0.2},{"gene":"NCAPH","stoichiometry":0.2},{"gene":"SCOC","stoichiometry":0.2},{"gene":"BRCA1","stoichiometry":0.2},{"gene":"H1F0","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID001264","total_profiled":1310},"omim":[{"mim_id":"603606","title":"RIBOSOMAL PROTEIN S6 KINASE A4; RPS6KA4","url":"https://www.omim.org/entry/603606"},{"mim_id":"602810","title":"HISTONE GENE CLUSTER 1, H3 HISTONE FAMILY, MEMBER A; HIST1H3A","url":"https://www.omim.org/entry/602810"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in all","driving_tissues":[{"tissue":"brain","ntpm":54.3}],"url":"https://www.proteinatlas.org/search/RPS6KA4"},"hgnc":{"alias_symbol":["RSK-B","MSK2"],"prev_symbol":[]},"alphafold":{"accession":"O75676","domains":[{"cath_id":"3.30.200.20","chopping":"20-75_82-117","consensus_level":"high","plddt":74.125,"start":20,"end":117},{"cath_id":"1.10.510.10","chopping":"122-323","consensus_level":"high","plddt":82.3198,"start":122,"end":323},{"cath_id":"3.30.200.20","chopping":"391-485","consensus_level":"high","plddt":81.9032,"start":391,"end":485},{"cath_id":"1.10.510.10","chopping":"490-715","consensus_level":"high","plddt":73.9993,"start":490,"end":715}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75676","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75676-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75676-F1-predicted_aligned_error_v6.png","plddt_mean":71.19},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=RPS6KA4","jax_strain_url":"https://www.jax.org/strain/search?query=RPS6KA4"},"sequence":{"accession":"O75676","fasta_url":"https://rest.uniprot.org/uniprotkb/O75676.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75676/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75676"}},"corpus_meta":[{"pmid":"12773393","id":"PMC_12773393","title":"MSK2 and MSK1 mediate the mitogen- and stress-induced phosphorylation of histone H3 and HMG-14.","date":"2003","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12773393","citation_count":411,"is_preprint":false},{"pmid":"11909979","id":"PMC_11909979","title":"MSK1 and MSK2 are required for the mitogen- and stress-induced phosphorylation of CREB and ATF1 in fibroblasts.","date":"2002","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/11909979","citation_count":374,"is_preprint":false},{"pmid":"18690222","id":"PMC_18690222","title":"The kinases MSK1 and MSK2 act as negative regulators of Toll-like receptor signaling.","date":"2008","source":"Nature immunology","url":"https://pubmed.ncbi.nlm.nih.gov/18690222","citation_count":270,"is_preprint":false},{"pmid":"9792677","id":"PMC_9792677","title":"RSK-B, a novel ribosomal S6 kinase family member, is a CREB kinase under dominant control of p38alpha mitogen-activated protein kinase (p38alphaMAPK).","date":"1998","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/9792677","citation_count":141,"is_preprint":false},{"pmid":"27350436","id":"PMC_27350436","title":"miR-93 regulates Msk2-mediated chromatin remodelling in diabetic nephropathy.","date":"2016","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/27350436","citation_count":55,"is_preprint":false},{"pmid":"12915720","id":"PMC_12915720","title":"MSK1 and MSK2 mediate mitogen- and stress-induced phosphorylation of histone H3: a controversy resolved.","date":"2003","source":"Science's STKE : signal transduction knowledge environment","url":"https://pubmed.ncbi.nlm.nih.gov/12915720","citation_count":54,"is_preprint":false},{"pmid":"23382072","id":"PMC_23382072","title":"MSK1 and MSK2 inhibit lipopolysaccharide-induced prostaglandin production via an interleukin-10 feedback loop.","date":"2013","source":"Molecular and cellular biology","url":"https://pubmed.ncbi.nlm.nih.gov/23382072","citation_count":35,"is_preprint":false},{"pmid":"16517600","id":"PMC_16517600","title":"The kinases MSK1 and MSK2 are required for epidermal growth factor-induced, but not tumor necrosis factor-induced, histone H3 Ser10 phosphorylation.","date":"2006","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/16517600","citation_count":35,"is_preprint":false},{"pmid":"21314333","id":"PMC_21314333","title":"Mice lacking MSK1 and MSK2 show reduced skin tumor development in a two-stage chemical carcinogenesis model.","date":"2011","source":"Cancer investigation","url":"https://pubmed.ncbi.nlm.nih.gov/21314333","citation_count":33,"is_preprint":false},{"pmid":"31889894","id":"PMC_31889894","title":"Sulforaphene induces apoptosis and inhibits the invasion of esophageal cancer cells through MSK2/CREB/Bcl-2 and cadherin pathway in vivo and in vitro.","date":"2019","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/31889894","citation_count":23,"is_preprint":false},{"pmid":"19933278","id":"PMC_19933278","title":"Differential regulation of mitogen- and stress-activated protein kinase-1 and -2 (MSK1 and MSK2) by CK2 following UV radiation.","date":"2009","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/19933278","citation_count":19,"is_preprint":false},{"pmid":"23599020","id":"PMC_23599020","title":"α-Lipoic acid prevents p53 degradation in colon cancer cells by blocking NF-κB induction of RPS6KA4.","date":"2013","source":"Anti-cancer drugs","url":"https://pubmed.ncbi.nlm.nih.gov/23599020","citation_count":18,"is_preprint":false},{"pmid":"30756420","id":"PMC_30756420","title":"MSK2 promotes proliferation and tumor formation in squamous cervical cancer via PAX8/RB-E2F1/cyclin A2 axis.","date":"2019","source":"Journal of cellular biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/30756420","citation_count":16,"is_preprint":false},{"pmid":"32963350","id":"PMC_32963350","title":"Discovery of a novel dual-target inhibitor against RSK1 and MSK2 to suppress growth of human colon cancer.","date":"2020","source":"Oncogene","url":"https://pubmed.ncbi.nlm.nih.gov/32963350","citation_count":16,"is_preprint":false},{"pmid":"19797274","id":"PMC_19797274","title":"MSK2 inhibits p53 activity in the absence of stress.","date":"2009","source":"Science signaling","url":"https://pubmed.ncbi.nlm.nih.gov/19797274","citation_count":16,"is_preprint":false},{"pmid":"24792438","id":"PMC_24792438","title":"Lysophosphatidic acid-induced IL-8 secretion involves MSK1 and MSK2 mediated activation of CREB1 in human fibroblast-like synoviocytes.","date":"2014","source":"Biochemical pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/24792438","citation_count":12,"is_preprint":false},{"pmid":"28930610","id":"PMC_28930610","title":"RPS6KA4/MIR1237 and AURKC promoter regions are differentially methylated in Wilms' tumor.","date":"2018","source":"Frontiers in bioscience (Elite edition)","url":"https://pubmed.ncbi.nlm.nih.gov/28930610","citation_count":7,"is_preprint":false},{"pmid":"37278562","id":"PMC_37278562","title":"Potentially functional genetic variants in RPS6KA4 and MAP2K5 in the MAPK signaling pathway predict HBV-related hepatocellular carcinoma survival.","date":"2023","source":"Molecular carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/37278562","citation_count":4,"is_preprint":false},{"pmid":"21385567","id":"PMC_21385567","title":"HCV-induced PKR activation is stimulated by the mitogen- and stress-activated protein kinase MSK2.","date":"2011","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/21385567","citation_count":4,"is_preprint":false},{"pmid":"39467851","id":"PMC_39467851","title":"Prim-O-glucosylcimifugin alleviates influenza virus-induced pneumonia in mice by inhibiting the TGF-β1/PI3KCD/MSK2/RELA signalling pathway.","date":"2024","source":"Archives of virology","url":"https://pubmed.ncbi.nlm.nih.gov/39467851","citation_count":3,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":10322,"output_tokens":3335,"usd":0.040495},"stage2":{"model":"claude-opus-4-6","input_tokens":6758,"output_tokens":6036,"usd":0.277035},"total_usd":0.31753,"stage1_batch_id":"msgbatch_011rkcQdVV1RaFq9XhcG6df6","stage2_batch_id":"msgbatch_01RzgrJafdF4EWHhj5mNi6dh","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"RPS6KA4 (RSK-B/MSK2) was identified as a substrate of p38α MAPK via an intracellular interaction screen; it is activated by p38αMAPK and more weakly by ERK1, contains two catalytic domains (N-terminal PKC-like and C-terminal CaM kinase-like), phosphorylates CREB and c-Fos peptides, drives CRE- and AP1-dependent reporter expression, and localizes to the cell nucleus where it co-translocates p38αMAPK.\",\n      \"method\": \"p38αMAPK-baited intracellular interaction screen, in vitro kinase assay, reporter gene assay, subcellular localization\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (interaction screen, in vitro kinase assay, reporter assay, localization) in single foundational paper\",\n      \"pmids\": [\"9792677\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"MSK1 and MSK2 are the major kinases responsible for mitogen- and stress-induced phosphorylation of histone H3 (Ser10, Ser28) and HMG-14 in fibroblasts; this was established using MSK1/MSK2 double-knockout mice showing severely reduced or abolished H3 and HMG-14 phosphorylation, while H3 acetylation remained unimpaired.\",\n      \"method\": \"MSK1/MSK2 double-knockout mouse fibroblasts, in vivo phosphorylation assay, immediate-early gene induction assay\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with specific phosphorylation readout, replicated across stimuli, highly cited foundational study\",\n      \"pmids\": [\"12773393\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"MSK1 and MSK2 are required for stress-induced (and partially mitogen-induced) phosphorylation of transcription factors CREB (Ser133) and ATF1 in primary embryonic fibroblasts, and MSK1/MSK2 double knockout reduces c-fos and junB transcription by ~50% in response to stress stimuli.\",\n      \"method\": \"MSK1/MSK2 single and double knockout mouse embryonic fibroblasts, phosphorylation assay, gene expression analysis\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with specific biochemical and transcriptional readouts, replicated across multiple stimuli\",\n      \"pmids\": [\"11909979\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"MSK1 and MSK2 act as negative regulators of TLR signaling by inducing transcription of DUSP1 and IL-10; they mediate phosphorylation of CREB and ATF1, enabling binding to the promoters of IL-10 and DUSP1 genes. MSK1/2 double-deficient mice show hypersensitivity to LPS-induced endotoxic shock and prolonged contact eczema.\",\n      \"method\": \"MSK1/MSK2 double-knockout mice, macrophage stimulation with LPS, chromatin immunoprecipitation (ChIP), cytokine measurement, in vivo endotoxin shock model\",\n      \"journal\": \"Nature immunology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO combined with ChIP and in vivo model, multiple orthogonal methods, highly cited\",\n      \"pmids\": [\"18690222\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"MSK1 and MSK2 are required for EGF-induced, but not TNF-induced, histone H3 Ser10 phosphorylation globally and at specific promoters (c-fos, IκBα), and are required for optimal EGF-induced c-fos transcription through control of both H3-Ser10 and CREB phosphorylation.\",\n      \"method\": \"MSK1/MSK2 knockdown, ChIP, in vivo phosphorylation assay, gene expression analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — KD with specific phosphorylation and transcriptional readouts, single lab\",\n      \"pmids\": [\"16517600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"CK2 protein kinase physically interacts with MSK2 (but not MSK1) and phosphorylates MSK2 at Ser324; CK2 inhibition or the S324A mutation impairs UV-induced MSK2 kinase activation. MSK2 (but not MSK1) is responsible for UV-induced phosphorylation of NF-κB p65 at Ser276, promoting NF-κB-responsive gene expression.\",\n      \"method\": \"Co-immunoprecipitation, site-directed mutagenesis (S324A), RNAi knockdown, ectopic expression rescue, in vivo phosphorylation assay, reporter gene assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — Co-IP, mutagenesis, RNAi rescue, multiple orthogonal methods establishing differential regulation and substrate\",\n      \"pmids\": [\"19933278\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"MSK2 inhibits p53 transcriptional activity in the absence of stress independently of its kinase activity and upstream MAPK signaling; MSK2 interacts with and inhibits the p53 coactivator p300, associates with the Noxa promoter, and apoptotic stimuli promote MSK2 degradation to relieve p53 inhibition.\",\n      \"method\": \"Co-immunoprecipitation, kinase-dead mutant analysis, ChIP, gene expression analysis, apoptosis assay\",\n      \"journal\": \"Science signaling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — Co-IP and ChIP with kinase-dead mutant, mechanistically detailed, single lab\",\n      \"pmids\": [\"19797274\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"MSK2 binds PKR and stimulates PKR phosphorylation in the context of HCV replication, apparently functioning as an adaptor independently of its own catalytic activity; MSK1 and RSK2 do not have this effect.\",\n      \"method\": \"Co-immunoprecipitation, in vivo phosphorylation assay, kinase-dead mutant analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — Co-IP and kinase-dead mutant, single lab, single paper\",\n      \"pmids\": [\"21385567\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"MSK1 and MSK2 regulate cox-2 mRNA stability via an IL-10 feedback mechanism: MSKs promote IL-10 production, which in turn promotes cox-2 mRNA degradation via p38/MK2 and the mRNA-binding protein TTP; MSK1/2 KO macrophages show elevated prostaglandin E2 and cox-2 protein due to reduced IL-10 and impaired mRNA degradation.\",\n      \"method\": \"MSK1/MSK2 knockout macrophages, IL-10 neutralization, mRNA stability assay, prostaglandin measurement, in vivo LPS model\",\n      \"journal\": \"Molecular and cellular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO with pathway dissection, multiple readouts, single lab\",\n      \"pmids\": [\"23382072\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"NF-κB plays a crucial role in RPS6KA4 gene expression: TNFα induces RPS6KA4 mRNA via NF-κB, and this is blocked by the NF-κB inhibitor BAY11-7082 or dominant-negative NF-κB; RPS6KA4 in turn inhibits p53 function, and its knockdown enhances α-lipoic acid-induced apoptosis in a p53-dependent manner.\",\n      \"method\": \"NF-κB inhibitor, dominant-negative NF-κB transfection, RPS6KA4 knockdown and restoration, apoptosis assay, microarray\",\n      \"journal\": \"Anti-cancer drugs\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — pharmacological and genetic inhibition with p53-dependent readout, single lab\",\n      \"pmids\": [\"23599020\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"MSK1 and MSK2 are the major CREB kinases in LPA-stimulated human fibroblast-like synoviocytes; both MSK1 and MSK2 mediate LPA-induced phosphorylation of CREB at Ser133 downstream of ERK1/2 and p38 MAPK, contributing to IL-8 and MCP-1 secretion.\",\n      \"method\": \"siRNA silencing of MSK1/MSK2, pharmacological inhibitor SB747651A, shRNA knockdown of CREB1, phosphorylation assay, cytokine measurement\",\n      \"journal\": \"Biochemical pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — siRNA/shRNA with specific biochemical and secretion readouts, single lab\",\n      \"pmids\": [\"24792438\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"miR-93 targets Msk2 (RPS6KA4) in podocytes; Msk2 phosphorylates histone H3 at Ser10 (H3S10), and miR-93-mediated suppression of Msk2 reduces H3S10 phosphorylation and nucleosomal dynamics, thereby ameliorating diabetic nephropathy-associated chromatin remodeling.\",\n      \"method\": \"Inducible transgenic miR-93 overexpression in podocytes, MSK2 knockdown, H3S10 phosphorylation assay, chromatin remodeling assay, mouse model of diabetic nephropathy\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo transgenic model with specific substrate readout, single lab\",\n      \"pmids\": [\"27350436\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"MSK2 promotes cervical cancer cell proliferation via phosphorylation of PAX8, which leads to suppression of RB phosphorylation and downstream activation of E2F1 and cyclin A2; MSK2 knockdown inhibited PAX8 phosphorylation, reduced E2F1 and cyclin A2 expression, and suppressed proliferation and tumor formation.\",\n      \"method\": \"MSK2 knockdown, western blot for PAX8/RB/E2F1/cyclin A2 phosphorylation, proliferation and tumor formation assays in vivo and in vitro\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — KD with pathway readout but no direct phosphorylation site mapping, single lab\",\n      \"pmids\": [\"30756420\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"RPS6KA4 (MSK2) is a nuclear serine/threonine kinase activated downstream of ERK1/2 and p38 MAPK (and phosphorylated by CK2 at Ser324 during UV stress) that phosphorylates histone H3 (Ser10/Ser28), HMG-14, CREB (Ser133), ATF1, NF-κB p65 (Ser276), and PAX8 to regulate immediate-early gene transcription, inflammatory cytokine production (including IL-10 and DUSP1 as negative feedback on TLR signaling), and chromatin remodeling; in the absence of stress it also non-catalytically inhibits p53 by interacting with the coactivator p300, and can act as an adaptor to stimulate PKR activation.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"RPS6KA4 (MSK2) is a dual-kinase-domain nuclear serine/threonine kinase activated downstream of both ERK1/2 and p38 MAPK that functions as a central chromatin and transcription-factor kinase linking mitogen and stress signaling to immediate-early gene expression, inflammatory cytokine regulation, and chromatin remodeling. MSK2, together with the paralog MSK1, is the major kinase responsible for stimulus-induced phosphorylation of histone H3 at Ser10 and Ser28, HMG-14, and the transcription factors CREB (Ser133) and ATF1, thereby driving transcription of c-fos, junB, IL-10, and DUSP1; loss of both MSKs causes hypersensitivity to endotoxic shock owing to defective IL-10-mediated negative feedback on TLR signaling [PMID:12773393, PMID:11909979, PMID:18690222]. MSK2 is selectively phosphorylated by CK2 at Ser324 during UV stress, enabling it to phosphorylate NF-κB p65 at Ser276 and activate NF-κB-dependent gene expression, a function not shared by MSK1 [PMID:19933278]. Independent of its catalytic activity, MSK2 inhibits p53 transcriptional function by sequestering the coactivator p300 at target promoters such as Noxa; apoptotic stimuli relieve this inhibition through MSK2 degradation [PMID:19797274].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Identification of MSK2 as a p38α MAPK substrate established it as a dual-kinase-domain nuclear kinase that phosphorylates CREB and activates CRE/AP1-dependent transcription, answering how p38 signaling reaches nuclear transcription-factor targets.\",\n      \"evidence\": \"Intracellular interaction screen baited with p38α, in vitro kinase assay, reporter assays, and subcellular fractionation in mammalian cells\",\n      \"pmids\": [\"9792677\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates beyond CREB peptides not yet defined\", \"Relative contribution of ERK versus p38 axis unclear\", \"No loss-of-function data\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Genetic knockout demonstrated that MSK1/MSK2 are required for stress-induced CREB and ATF1 phosphorylation and for full immediate-early gene (c-fos, junB) induction, resolving which kinases are the physiological CREB Ser133 kinases downstream of MAPK cascades.\",\n      \"evidence\": \"MSK1/MSK2 single and double knockout mouse embryonic fibroblasts with phosphorylation and transcription readouts\",\n      \"pmids\": [\"11909979\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Individual contributions of MSK1 versus MSK2 not fully separated\", \"Stimulus-specific roles (mitogen vs. stress) not delineated for all targets\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Double-knockout studies established MSK1/MSK2 as the major histone H3 Ser10/Ser28 and HMG-14 kinases in mitogen- and stress-stimulated fibroblasts, linking MAPK signaling directly to chromatin remodeling.\",\n      \"evidence\": \"MSK1/MSK2 double-knockout mouse fibroblasts with in vivo histone phosphorylation assays across multiple stimuli\",\n      \"pmids\": [\"12773393\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Locus-specific versus global H3 phosphorylation roles not resolved\", \"Functional consequence of H3 phosphorylation on gene transcription not directly tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"ChIP-based promoter analysis showed that MSK1/MSK2 mediate EGF-induced H3 Ser10 phosphorylation at specific gene promoters (c-fos, IκBα) and are required for optimal c-fos transcription, demonstrating locus-specific chromatin kinase function.\",\n      \"evidence\": \"MSK1/MSK2 knockdown with ChIP and gene expression analysis in stimulated cells\",\n      \"pmids\": [\"16517600\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"TNF-induced H3 phosphorylation uses a different kinase — identity unknown\", \"Genome-wide target promoter landscape not mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"In vivo knockout studies revealed that MSK1/MSK2 serve as critical anti-inflammatory effectors by inducing IL-10 and DUSP1 via CREB/ATF1 phosphorylation, establishing a negative-feedback loop on TLR signaling that limits endotoxic shock and contact eczema.\",\n      \"evidence\": \"MSK1/MSK2 double-knockout mice, macrophage LPS stimulation, ChIP on IL-10 and DUSP1 promoters, in vivo endotoxin shock and eczema models\",\n      \"pmids\": [\"18690222\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative individual contributions of MSK1 versus MSK2 to IL-10 induction not separated\", \"Downstream transcriptional programs beyond IL-10/DUSP1 not profiled\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Two parallel discoveries established MSK2-specific functions: CK2 phosphorylates MSK2 at Ser324 to enable UV-induced NF-κB p65 Ser276 phosphorylation (distinguishing MSK2 from MSK1), and MSK2 inhibits p53 independently of kinase activity by blocking p300 coactivator function, revealing a non-catalytic adaptor role.\",\n      \"evidence\": \"Co-IP, S324A mutagenesis, RNAi rescue for CK2–NF-κB axis; Co-IP, kinase-dead mutant, ChIP at Noxa promoter for p53–p300 axis\",\n      \"pmids\": [\"19933278\", \"19797274\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of MSK2–p300 interaction unknown\", \"Whether CK2-dependent activation of MSK2 extends beyond UV stress untested\", \"In vivo relevance of p53 inhibition not confirmed with knockout\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"MSK2 was found to stimulate PKR phosphorylation during HCV replication as an adaptor, independent of its own kinase activity, extending the non-catalytic adaptor paradigm to antiviral signaling.\",\n      \"evidence\": \"Co-immunoprecipitation and kinase-dead mutant analysis in HCV-replicating cells\",\n      \"pmids\": [\"21385567\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which MSK2 binding activates PKR not defined\", \"Not independently confirmed by another group\", \"In vivo relevance during viral infection untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The MSK-IL-10 axis was extended to post-transcriptional control: MSK1/2-driven IL-10 promotes cox-2 mRNA degradation via p38/MK2/TTP, explaining elevated prostaglandin E2 in MSK-deficient macrophages and broadening the anti-inflammatory reach of MSKs. Separately, NF-κB was shown to transcriptionally induce RPS6KA4 itself, creating a feedforward loop coupling NF-κB activation to p53 suppression.\",\n      \"evidence\": \"MSK1/2 KO macrophages with mRNA stability and prostaglandin assays; NF-κB inhibitor and dominant-negative experiments with MSK2 knockdown/rescue and apoptosis assays\",\n      \"pmids\": [\"23382072\", \"23599020\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct NF-κB binding sites in the RPS6KA4 promoter not mapped\", \"Relative roles of MSK1 versus MSK2 in cox-2 mRNA regulation unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"miR-93 was identified as a physiological suppressor of MSK2 in podocytes, linking MSK2-driven H3 Ser10 phosphorylation and chromatin dynamics to diabetic nephropathy pathogenesis.\",\n      \"evidence\": \"Inducible miR-93 transgenic mice, MSK2 knockdown in podocytes, H3S10 phosphorylation and chromatin remodeling assays, diabetic nephropathy model\",\n      \"pmids\": [\"27350436\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Target genes affected by MSK2-driven H3S10 phosphorylation in podocytes not identified\", \"Whether MSK1 compensates in podocytes not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: the genome-wide set of MSK2-specific (versus MSK1-redundant) chromatin and transcription-factor targets; the structural basis of MSK2's non-catalytic interactions with p300 and PKR; and whether MSK2-selective functions identified in vitro (NF-κB p65 phosphorylation, p53 inhibition, PKR activation) are recapitulated with MSK2 single-knockout models in vivo.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No MSK2 single-knockout phenotype characterized in vivo for p53/NF-κB/PKR axes\", \"No structural model of MSK2–p300 or MSK2–PKR complexes\", \"Genome-wide MSK2-specific ChIP-seq targets not available\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 4, 5, 10, 11]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 2, 5]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [1, 4, 11]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [6, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 4, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0162582\", \"supporting_discovery_ids\": [0, 5, 9]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 5, 9]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [1, 4, 11]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 3, 4]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"MAPK14\",\n      \"CREB1\",\n      \"ATF1\",\n      \"RELA\",\n      \"CSNK2A1\",\n      \"EP300\",\n      \"EIF2AK2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```\n\nWait, I need to fix the pathway entries — I accidentally included a \"GO:0162582\" which is not a valid term. Let me correct:\n\n```json\n{\n  \"mechanistic_narrative\": \"RPS6KA4 (MSK2) is a dual-kinase-domain nuclear serine/threonine kinase activated downstream of both ERK1/2 and p38 MAPK that functions as a central chromatin and transcription-factor kinase linking mitogen and stress signaling to immediate-early gene expression, inflammatory cytokine regulation, and chromatin remodeling. MSK2, together with the paralog MSK1, is the major kinase responsible for stimulus-induced phosphorylation of histone H3 at Ser10 and Ser28, HMG-14, and the transcription factors CREB (Ser133) and ATF1, thereby driving transcription of c-fos, junB, IL-10, and DUSP1; loss of both MSKs causes hypersensitivity to endotoxic shock owing to defective IL-10-mediated negative feedback on TLR signaling [PMID:12773393, PMID:11909979, PMID:18690222]. MSK2 is selectively phosphorylated by CK2 at Ser324 during UV stress, enabling it to phosphorylate NF-κB p65 at Ser276 and activate NF-κB-dependent gene expression, a function not shared by MSK1 [PMID:19933278]. Independent of its catalytic activity, MSK2 inhibits p53 transcriptional function by sequestering the coactivator p300 at target promoters such as Noxa; apoptotic stimuli relieve this inhibition through MSK2 degradation [PMID:19797274].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Identification of MSK2 as a p38α MAPK substrate established it as a dual-kinase-domain nuclear kinase that phosphorylates CREB and activates CRE/AP1-dependent transcription, answering how p38 signaling reaches nuclear transcription-factor targets.\",\n      \"evidence\": \"Intracellular interaction screen baited with p38α, in vitro kinase assay, reporter assays, and subcellular fractionation in mammalian cells\",\n      \"pmids\": [\"9792677\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates beyond CREB peptides not yet defined\", \"Relative contribution of ERK versus p38 axis unclear\", \"No loss-of-function data\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Genetic knockout demonstrated that MSK1/MSK2 are required for stress-induced CREB and ATF1 phosphorylation and for full immediate-early gene (c-fos, junB) induction, resolving which kinases are the physiological CREB Ser133 kinases downstream of MAPK cascades.\",\n      \"evidence\": \"MSK1/MSK2 single and double knockout mouse embryonic fibroblasts with phosphorylation and transcription readouts\",\n      \"pmids\": [\"11909979\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Individual contributions of MSK1 versus MSK2 not fully separated\", \"Stimulus-specific roles (mitogen vs. stress) not delineated for all targets\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Double-knockout studies established MSK1/MSK2 as the major histone H3 Ser10/Ser28 and HMG-14 kinases in mitogen- and stress-stimulated fibroblasts, linking MAPK signaling directly to chromatin remodeling.\",\n      \"evidence\": \"MSK1/MSK2 double-knockout mouse fibroblasts with in vivo histone phosphorylation assays across multiple stimuli\",\n      \"pmids\": [\"12773393\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Locus-specific versus global H3 phosphorylation roles not resolved\", \"Functional consequence of H3 phosphorylation on gene transcription not directly tested\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"ChIP-based promoter analysis showed that MSK1/MSK2 mediate EGF-induced H3 Ser10 phosphorylation at specific gene promoters (c-fos, IκBα) and are required for optimal c-fos transcription, demonstrating locus-specific chromatin kinase function.\",\n      \"evidence\": \"MSK1/MSK2 knockdown with ChIP and gene expression analysis in stimulated cells\",\n      \"pmids\": [\"16517600\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"TNF-induced H3 phosphorylation uses a different kinase — identity unknown\", \"Genome-wide target promoter landscape not mapped\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"In vivo knockout studies revealed that MSK1/MSK2 serve as critical anti-inflammatory effectors by inducing IL-10 and DUSP1 via CREB/ATF1 phosphorylation, establishing a negative-feedback loop on TLR signaling that limits endotoxic shock and contact eczema.\",\n      \"evidence\": \"MSK1/MSK2 double-knockout mice, macrophage LPS stimulation, ChIP on IL-10 and DUSP1 promoters, in vivo endotoxin shock and eczema models\",\n      \"pmids\": [\"18690222\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relative individual contributions of MSK1 versus MSK2 to IL-10 induction not separated\", \"Downstream transcriptional programs beyond IL-10/DUSP1 not profiled\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Two parallel discoveries established MSK2-specific functions: CK2 phosphorylates MSK2 at Ser324 to enable UV-induced NF-κB p65 Ser276 phosphorylation (distinguishing MSK2 from MSK1), and MSK2 inhibits p53 independently of kinase activity by blocking p300 coactivator function, revealing a non-catalytic adaptor role.\",\n      \"evidence\": \"Co-IP, S324A mutagenesis, RNAi rescue for CK2–NF-κB axis; Co-IP, kinase-dead mutant, ChIP at Noxa promoter for p53–p300 axis\",\n      \"pmids\": [\"19933278\", \"19797274\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of MSK2–p300 interaction unknown\", \"Whether CK2-dependent activation of MSK2 extends beyond UV stress untested\", \"In vivo relevance of p53 inhibition not confirmed with knockout\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"MSK2 was found to stimulate PKR phosphorylation during HCV replication as an adaptor, independent of its own kinase activity, extending the non-catalytic adaptor paradigm to antiviral signaling.\",\n      \"evidence\": \"Co-immunoprecipitation and kinase-dead mutant analysis in HCV-replicating cells\",\n      \"pmids\": [\"21385567\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which MSK2 binding activates PKR not defined\", \"Not independently confirmed by another group\", \"In vivo relevance during viral infection untested\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The MSK-IL-10 axis was extended to post-transcriptional control: MSK1/2-driven IL-10 promotes cox-2 mRNA degradation via p38/MK2/TTP, explaining elevated prostaglandin E2 in MSK-deficient macrophages. Separately, NF-κB was shown to transcriptionally induce RPS6KA4 itself, creating a feedforward loop coupling NF-κB activation to p53 suppression.\",\n      \"evidence\": \"MSK1/2 KO macrophages with mRNA stability and prostaglandin assays; NF-κB inhibitor and dominant-negative experiments with MSK2 knockdown/rescue and apoptosis assays\",\n      \"pmids\": [\"23382072\", \"23599020\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct NF-κB binding sites in the RPS6KA4 promoter not mapped\", \"Relative roles of MSK1 versus MSK2 in cox-2 mRNA regulation unclear\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"miR-93 was identified as a physiological suppressor of MSK2 in podocytes, linking MSK2-driven H3 Ser10 phosphorylation and chromatin dynamics to diabetic nephropathy pathogenesis.\",\n      \"evidence\": \"Inducible miR-93 transgenic mice, MSK2 knockdown in podocytes, H3S10 phosphorylation and chromatin remodeling assays, diabetic nephropathy model\",\n      \"pmids\": [\"27350436\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Target genes affected by MSK2-driven H3S10 phosphorylation in podocytes not identified\", \"Whether MSK1 compensates in podocytes not addressed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include: the genome-wide set of MSK2-specific (versus MSK1-redundant) chromatin and transcription-factor targets; the structural basis of MSK2's non-catalytic interactions with p300 and PKR; and whether MSK2-selective functions identified in vitro (NF-κB p65 phosphorylation, p53 inhibition, PKR activation) are recapitulated with MSK2 single-knockout models in vivo.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No MSK2 single-knockout phenotype characterized in vivo for p53/NF-κB/PKR axes\", \"No structural model of MSK2–p300 or MSK2–PKR complexes\", \"Genome-wide MSK2-specific ChIP-seq targets not available\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 2, 4, 5, 10, 11]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 1, 2, 5]},\n      {\"term_id\": \"GO:0042393\", \"supporting_discovery_ids\": [1, 4, 11]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [6, 7]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [6, 9]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [0, 4, 6]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 5, 9]},\n      {\"term_id\": \"R-HSA-4839726\", \"supporting_discovery_ids\": [1, 4, 11]},\n      {\"term_id\": \"R-HSA-74160\", \"supporting_discovery_ids\": [2, 3, 4]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [3, 8]},\n      {\"term_id\": \"R-HSA-5357801\", \"supporting_discovery_ids\": [6, 9]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"MAPK14\",\n      \"CREB1\",\n      \"ATF1\",\n      \"RELA\",\n      \"CSNK2A1\",\n      \"EP300\",\n      \"EIF2AK2\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}