{"gene":"STK16","run_date":"2026-06-10T07:46:43","timeline":{"discoveries":[{"year":1998,"finding":"PKL12 (STK16) encodes a serine/threonine protein kinase with intrinsic kinase activity capable of phosphorylating enolase and promoting autophosphorylation, as demonstrated using E. coli-purified protein in in vitro kinase assays.","method":"In vitro kinase assay with bacterially purified protein; substrate phosphorylation and autophosphorylation","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro reconstituted kinase assay with purified recombinant protein demonstrating catalytic activity","pmids":["9712705"],"is_preprint":false},{"year":2001,"finding":"PKL12/STK16 physically interacts with N-acetylglucosamine kinase (GlcNAcK), confirmed by yeast two-hybrid and in vitro/in vivo binding assays. GlcNAcK colocalizes with PKL12 in vesicular structures near the cell membrane. GlcNAcK is not a substrate for PKL12 and does not modulate PKL12 autophosphorylation, but functional GlcNAcK greatly enhances PKL12 kinase activity on a defined substrate protein in vitro.","method":"Yeast two-hybrid screen, in vitro binding confirmation, in vivo co-localization, in vitro kinase assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — interaction confirmed by multiple orthogonal methods (yeast two-hybrid, in vitro pulldown, in vivo co-localization, in vitro kinase assay) in a single study","pmids":["11741987"],"is_preprint":false},{"year":2005,"finding":"Endogenous STK16/PKL12 localizes to the Golgi apparatus in NIH/3T3 and NRK cells; treatment with brefeldin A or nocodazole (Golgi disorganization agents) causes STK16 to translocate to the nuclear compartment. Constitutive overexpression also drives nuclear accumulation. A kinase-dead mutant (E202A) retains both Golgi association and nuclear translocation, indicating these localizations are independent of kinase activity. STK16 overexpression enhances VEGF production and secretion in vitro and increases tumor vascularity in vivo.","method":"Indirect immunofluorescence, subcellular fractionation, kinase-dead mutant (E202A), retroviral overexpression, in vivo xenograft model","journal":"Experimental cell research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple orthogonal localization methods, functional mutagenesis, and in vivo confirmation in single study","pmids":["16310770"],"is_preprint":false},{"year":2016,"finding":"STK16-IN-1 was identified as a highly selective, ATP-competitive inhibitor of STK16 (IC50 = 0.295 µM, S score(1) = 0.0 across kinome). In MCF-7 cells, STK16-IN-1 treatment reduces cell number and causes accumulation of binucleated cells, phenocopying RNAi knockdown of STK16, establishing STK16 kinase activity as required for normal cell division.","method":"Biochemical kinase inhibition assay, KinomeScan profiling, RNAi knockdown, cell number/binucleation assay","journal":"ACS chemical biology","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — ATP-competitive mechanism established biochemically, phenotype confirmed by both pharmacological inhibition and genetic knockdown (two orthogonal methods)","pmids":["27082499"],"is_preprint":false},{"year":2017,"finding":"STK16 localizes to the Golgi throughout the cell cycle and directly binds actin, regulating actin dynamics in a concentration- and kinase activity-dependent manner. STK16 knockdown or kinase inhibition disrupts actin polymers, causes Golgi fragmentation, delays mitotic entry, prolongs mitosis, and causes prometaphase and cytokinesis arrest.","method":"In vitro actin-binding assay, siRNA knockdown, pharmacological kinase inhibition, live-cell imaging, immunofluorescence","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — direct actin binding established in vitro; loss-of-function phenotypes confirmed by both genetic knockdown and pharmacological inhibition, multiple readouts","pmids":["28294156"],"is_preprint":false},{"year":2019,"finding":"STK16 autophosphorylates at Thr185, Ser197, and Tyr198 within its activation segment. Mutation of Tyr198 alone significantly reduces kinase activity, abolishes Golgi and membrane localization, and impairs cell cycle progression, identifying Tyr198 as the essential autophosphorylation site for STK16 localization and function.","method":"Site-directed mutagenesis of autophosphorylation sites, in vitro kinase assay, subcellular localization studies (immunofluorescence/fractionation), cell cycle analysis","journal":"International journal of molecular sciences","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — mutagenesis combined with in vitro kinase assay and localization studies establishing mechanistic link between specific phosphorylation site and kinase function","pmids":["31574902"],"is_preprint":false},{"year":2024,"finding":"STK16 directly phosphorylates c-MYC at serine 452, which prevents c-MYC degradation via the ubiquitin-proteasome pathway. Colorectal cancer cell proliferation driven by STK16 depends on this phosphorylation event. STK16 knockout or pharmacological inhibition reduces c-MYC protein levels and curtails tumor growth in vivo.","method":"Immunoprecipitation, immunoblot (phospho-specific), in vitro kinase assay, site-directed mutagenesis (S452), ubiquitination assay, cell proliferation assays, in vivo animal model with STK16 KO/inhibitor","journal":"Molecular medicine (Cambridge, Mass.)","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — c-MYC S452 phosphorylation established by immunoprecipitation and functional rescue, but single lab and abstract-level description of methods without full mechanistic reconstitution","pmids":["38622518"],"is_preprint":false},{"year":2022,"finding":"STK16 knockdown inhibits LUAD cell proliferation and promotes apoptosis via the AKT1 pathway. STK16 is a transcriptional target of ETS1; miR-181a-5p (delivered via M1 macrophage exosomes) suppresses ETS1, thereby reducing STK16 expression and promoting apoptosis.","method":"siRNA knockdown, CCK-8 proliferation assay, apoptosis assay, luciferase reporter assay, ChIP assay, Western blotting, mouse xenograft model","journal":"Cancer science","confidence":"Medium","confidence_rationale":"Tier 2–3 / Moderate — loss-of-function phenotype with AKT1 pathway readout; ChIP assay links ETS1 to STK16 transcription; single lab with multiple methods but primarily upstream regulatory finding","pmids":["35092121"],"is_preprint":false}],"current_model":"STK16 is a myristoylated and palmitoylated serine/threonine kinase constitutively localized to the Golgi (dependent on autophosphorylation at Tyr198), where it directly binds actin and regulates actin dynamics in a kinase-activity-dependent manner to maintain Golgi structure and support cell cycle progression through mitosis and cytokinesis; it also shuttles to the nucleus upon Golgi disruption or overexpression, interacts with GlcNAcK (which allosterically enhances its kinase activity), phosphorylates c-MYC at Ser452 to protect it from proteasomal degradation, and its activity is required for VEGF secretion and smooth muscle contraction downstream of non-adrenergic stimuli."},"narrative":{"mechanistic_narrative":"STK16 is an intrinsically active serine/threonine protein kinase that links Golgi-associated actin dynamics to cell cycle progression and to control of oncogenic signaling [PMID:9712705, PMID:28294156]. It is constitutively localized to the Golgi apparatus throughout the cell cycle, where it directly binds actin and regulates actin polymer organization in a concentration- and kinase-activity-dependent manner; loss of STK16 by knockdown or kinase inhibition disrupts actin polymers, fragments the Golgi, delays mitotic entry, and produces prometaphase and cytokinesis arrest with accumulation of binucleated cells [PMID:27082499, PMID:28294156]. Golgi and membrane targeting depend on autophosphorylation within the activation segment, with Tyr198 being the essential site whose mutation reduces kinase activity, abolishes Golgi/membrane localization, and impairs cell cycle progression [PMID:31574902]. Upon Golgi disorganization or overexpression, STK16 translocates to the nucleus independently of its catalytic activity [PMID:16310770]. Its kinase activity is enhanced by physical interaction with N-acetylglucosamine kinase (GlcNAcK), which binds STK16 but is not itself a substrate [PMID:11741987]. STK16 also drives proliferative signaling: it directly phosphorylates c-MYC at Ser452 to protect c-MYC from ubiquitin-proteasome degradation, supporting colorectal cancer growth [PMID:38622518], and its overexpression enhances VEGF production and secretion and increases tumor vascularity [PMID:16310770]. Highly selective ATP-competitive inhibition phenocopies genetic loss, establishing that the kinase activity is required for these functions [PMID:27082499].","teleology":[{"year":1998,"claim":"Establishing that STK16/PKL12 is a bona fide catalytically active kinase was the founding question, settled by showing it phosphorylates substrate and autophosphorylates in isolation.","evidence":"In vitro kinase assay with bacterially purified recombinant protein, enolase substrate and autophosphorylation","pmids":["9712705"],"confidence":"High","gaps":["No physiological substrate identified","No cellular localization or pathway context established"]},{"year":2001,"claim":"Identifying a binding partner that modulates activity addressed how STK16 catalysis is regulated, showing GlcNAcK binds and allosterically enhances kinase activity without being a substrate.","evidence":"Yeast two-hybrid screen, in vitro pulldown, in vivo co-localization in vesicular structures, in vitro kinase assay","pmids":["11741987"],"confidence":"High","gaps":["Mechanism by which GlcNAcK enhances activity not resolved","Physiological relevance of the interaction not tested in loss-of-function context"]},{"year":2005,"claim":"Defining where STK16 acts addressed its compartmental role, establishing constitutive Golgi localization with kinase-independent nuclear translocation upon Golgi disruption, and linking it to VEGF secretion.","evidence":"Immunofluorescence, subcellular fractionation, kinase-dead E202A mutant, retroviral overexpression, in vivo xenograft","pmids":["16310770"],"confidence":"High","gaps":["Functional consequence of nuclear pool unknown","Mechanism linking STK16 to VEGF secretion not defined","Golgi-targeting determinants not identified"]},{"year":2016,"claim":"A selective ATP-competitive inhibitor (STK16-IN-1) addressed whether catalytic activity itself drives the cell division phenotype, showing pharmacological inhibition phenocopies RNAi knockdown.","evidence":"Biochemical kinase inhibition, KinomeScan selectivity profiling, RNAi knockdown, binucleation/cell number assays in MCF-7","pmids":["27082499"],"confidence":"High","gaps":["Relevant phosphorylation substrate for cell division not identified","Mechanism producing binucleation not resolved"]},{"year":2017,"claim":"Connecting STK16 to a direct molecular target addressed how it controls Golgi and mitosis, showing direct actin binding and kinase-activity-dependent regulation of actin dynamics underlying Golgi integrity and mitotic progression.","evidence":"In vitro actin-binding assay, siRNA knockdown, pharmacological inhibition, live-cell imaging, immunofluorescence","pmids":["28294156"],"confidence":"High","gaps":["Whether actin is a phosphorylation substrate not established","Molecular link between actin regulation and cytokinesis arrest unresolved"]},{"year":2019,"claim":"Mapping the activation-segment autophosphorylation sites addressed how STK16 activity and localization are coupled, identifying Tyr198 as the essential site for both kinase activity and Golgi/membrane targeting.","evidence":"Site-directed mutagenesis of Thr185/Ser197/Tyr198, in vitro kinase assay, localization studies, cell cycle analysis","pmids":["31574902"],"confidence":"High","gaps":["Upstream trigger of activation-segment autophosphorylation unknown","How Tyr198 phosphorylation drives membrane association mechanistically unresolved"]},{"year":2022,"claim":"Placing STK16 in a regulatory and survival circuit addressed its role in lung cancer, showing it acts via the AKT1 pathway and is transcriptionally controlled by ETS1 under miR-181a-5p regulation.","evidence":"siRNA knockdown, proliferation/apoptosis assays, luciferase reporter, ChIP, Western blot, mouse xenograft","pmids":["35092121"],"confidence":"Medium","gaps":["Direct STK16 substrate in the AKT1 axis not identified","Whether STK16 acts upstream or in parallel to AKT1 not resolved"]},{"year":2024,"claim":"Identifying a direct phosphosubstrate addressed how STK16 promotes tumor growth, showing it phosphorylates c-MYC at Ser452 to block proteasomal degradation in colorectal cancer.","evidence":"Immunoprecipitation, phospho-specific immunoblot, in vitro kinase assay, S452 mutagenesis, ubiquitination assay, STK16 KO/inhibitor in vivo","pmids":["38622518"],"confidence":"Medium","gaps":["Single-lab finding without full mechanistic reconstitution","How Golgi-localized STK16 accesses c-MYC not addressed","Generality beyond colorectal context untested"]},{"year":null,"claim":"How STK16's Golgi/actin role mechanistically integrates with its substrate phosphorylation events (c-MYC, AKT1 axis) and VEGF secretion into a single signaling logic remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified substrate map linking Golgi actin regulation to nuclear/oncogenic targets","Physiological upstream activators of STK16 unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,6]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,5]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[3]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[2,4,5]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[2]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[5]}],"pathway":[{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[3,4]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[6,7]}],"complexes":[],"partners":["NAGK","ACTB","MYC"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"O75716","full_name":"Serine/threonine-protein kinase 16","aliases":["Myristoylated and palmitoylated serine/threonine-protein kinase","MPSK","Protein kinase PKL12","TGF-beta-stimulated factor 1","TSF-1","Tyrosine-protein kinase STK16","hPSK"],"length_aa":305,"mass_kda":34.7,"function":"Membrane-associated protein kinase that phosphorylates on serine and threonine residues. In vitro substrates include DRG1, ENO1 and EIF4EBP1. Also autophosphorylates. May be involved in secretory vesicle trafficking or intracellular signaling. May have a role in regulating stromal-epithelial interactions that occur during ductal morphogenesis in the mammary gland. May be involved in TGF-beta signaling. Able to autophosphorylate on Tyr residue; it is however unclear whether it has tyrosine-protein kinase toward other proteins","subcellular_location":"Cytoplasm, perinuclear region; Membrane","url":"https://www.uniprot.org/uniprotkb/O75716/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/STK16","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/STK16","total_profiled":1310},"omim":[{"mim_id":"606431","title":"UDP-GLYCOSYLTRANSFERASE 1 FAMILY, POLYPEPTIDE A6; UGT1A6","url":"https://www.omim.org/entry/606431"},{"mim_id":"604719","title":"SERINE/THREONINE PROTEIN KINASE 16; STK16","url":"https://www.omim.org/entry/604719"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Cytosol","reliability":"Supported"},{"location":"Nucleoplasm","reliability":"Additional"},{"location":"Nuclear bodies","reliability":"Additional"},{"location":"Plasma membrane","reliability":"Additional"},{"location":"Primary cilium","reliability":"Additional"},{"location":"Primary cilium tip","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/STK16"},"hgnc":{"alias_symbol":["PKL12","MPSK"],"prev_symbol":[]},"alphafold":{"accession":"O75716","domains":[{"cath_id":"3.30.200.20","chopping":"11-98","consensus_level":"high","plddt":94.7519,"start":11,"end":98},{"cath_id":"1.10.510.10","chopping":"103-292","consensus_level":"high","plddt":96.6403,"start":103,"end":292}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/O75716","model_url":"https://alphafold.ebi.ac.uk/files/AF-O75716-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-O75716-F1-predicted_aligned_error_v6.png","plddt_mean":93.06},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=STK16","jax_strain_url":"https://www.jax.org/strain/search?query=STK16"},"sequence":{"accession":"O75716","fasta_url":"https://rest.uniprot.org/uniprotkb/O75716.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/O75716/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/O75716"}},"corpus_meta":[{"pmid":"35092121","id":"PMC_35092121","title":"Exosomes from M1-polarized macrophages promote apoptosis in lung adenocarcinoma via the miR-181a-5p/ETS1/STK16 axis.","date":"2022","source":"Cancer science","url":"https://pubmed.ncbi.nlm.nih.gov/35092121","citation_count":38,"is_preprint":false},{"pmid":"11741987","id":"PMC_11741987","title":"Functional interaction between the Ser/Thr kinase PKL12 and N-acetylglucosamine kinase, a prominent enzyme implicated in the salvage pathway for GlcNAc recycling.","date":"2001","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/11741987","citation_count":26,"is_preprint":false},{"pmid":"16310770","id":"PMC_16310770","title":"Nucleocytoplasmic shuttling of STK16 (PKL12), a Golgi-resident serine/threonine kinase involved in VEGF expression regulation.","date":"2005","source":"Experimental cell research","url":"https://pubmed.ncbi.nlm.nih.gov/16310770","citation_count":22,"is_preprint":false},{"pmid":"28294156","id":"PMC_28294156","title":"STK16 regulates actin dynamics to control Golgi organization and cell cycle.","date":"2017","source":"Scientific reports","url":"https://pubmed.ncbi.nlm.nih.gov/28294156","citation_count":20,"is_preprint":false},{"pmid":"9712705","id":"PMC_9712705","title":"Cloning, expression analysis, and functional characterization of PKL12, a member of a new subfamily of ser/thr kinases.","date":"1998","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/9712705","citation_count":20,"is_preprint":false},{"pmid":"27082499","id":"PMC_27082499","title":"Discovery of a Highly Selective STK16 Kinase Inhibitor.","date":"2016","source":"ACS chemical biology","url":"https://pubmed.ncbi.nlm.nih.gov/27082499","citation_count":19,"is_preprint":false},{"pmid":"30974739","id":"PMC_30974739","title":"Serine/Threonine Protein Kinase STK16.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/30974739","citation_count":17,"is_preprint":false},{"pmid":"31867686","id":"PMC_31867686","title":"The STK16 inhibitor STK16-IN-1 inhibits non-adrenergic and non-neurogenic smooth muscle contractions in the human prostate and the human male detrusor.","date":"2019","source":"Naunyn-Schmiedeberg's archives of pharmacology","url":"https://pubmed.ncbi.nlm.nih.gov/31867686","citation_count":8,"is_preprint":false},{"pmid":"31574902","id":"PMC_31574902","title":"Tyr198 is the Essential Autophosphorylation Site for STK16 Localization and Kinase Activity.","date":"2019","source":"International journal of molecular sciences","url":"https://pubmed.ncbi.nlm.nih.gov/31574902","citation_count":5,"is_preprint":false},{"pmid":"38622518","id":"PMC_38622518","title":"STK16 promoted colorectal cancer progress in a c-MYC signaling-dependent manner.","date":"2024","source":"Molecular medicine (Cambridge, Mass.)","url":"https://pubmed.ncbi.nlm.nih.gov/38622518","citation_count":3,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6881,"output_tokens":2298,"usd":0.027557,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":9337,"output_tokens":3065,"usd":0.061655,"stage2_stop_reason":"end_turn"},"total_usd":0.089212,"stage1_batch_id":"msgbatch_013LWZZT6MWaqB9qyTSeQBmU","stage2_batch_id":"msgbatch_0194ZzQaTGNpruoNJBbEMbt3","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1998,\n      \"finding\": \"PKL12 (STK16) encodes a serine/threonine protein kinase with intrinsic kinase activity capable of phosphorylating enolase and promoting autophosphorylation, as demonstrated using E. coli-purified protein in in vitro kinase assays.\",\n      \"method\": \"In vitro kinase assay with bacterially purified protein; substrate phosphorylation and autophosphorylation\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro reconstituted kinase assay with purified recombinant protein demonstrating catalytic activity\",\n      \"pmids\": [\"9712705\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PKL12/STK16 physically interacts with N-acetylglucosamine kinase (GlcNAcK), confirmed by yeast two-hybrid and in vitro/in vivo binding assays. GlcNAcK colocalizes with PKL12 in vesicular structures near the cell membrane. GlcNAcK is not a substrate for PKL12 and does not modulate PKL12 autophosphorylation, but functional GlcNAcK greatly enhances PKL12 kinase activity on a defined substrate protein in vitro.\",\n      \"method\": \"Yeast two-hybrid screen, in vitro binding confirmation, in vivo co-localization, in vitro kinase assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — interaction confirmed by multiple orthogonal methods (yeast two-hybrid, in vitro pulldown, in vivo co-localization, in vitro kinase assay) in a single study\",\n      \"pmids\": [\"11741987\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Endogenous STK16/PKL12 localizes to the Golgi apparatus in NIH/3T3 and NRK cells; treatment with brefeldin A or nocodazole (Golgi disorganization agents) causes STK16 to translocate to the nuclear compartment. Constitutive overexpression also drives nuclear accumulation. A kinase-dead mutant (E202A) retains both Golgi association and nuclear translocation, indicating these localizations are independent of kinase activity. STK16 overexpression enhances VEGF production and secretion in vitro and increases tumor vascularity in vivo.\",\n      \"method\": \"Indirect immunofluorescence, subcellular fractionation, kinase-dead mutant (E202A), retroviral overexpression, in vivo xenograft model\",\n      \"journal\": \"Experimental cell research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple orthogonal localization methods, functional mutagenesis, and in vivo confirmation in single study\",\n      \"pmids\": [\"16310770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"STK16-IN-1 was identified as a highly selective, ATP-competitive inhibitor of STK16 (IC50 = 0.295 µM, S score(1) = 0.0 across kinome). In MCF-7 cells, STK16-IN-1 treatment reduces cell number and causes accumulation of binucleated cells, phenocopying RNAi knockdown of STK16, establishing STK16 kinase activity as required for normal cell division.\",\n      \"method\": \"Biochemical kinase inhibition assay, KinomeScan profiling, RNAi knockdown, cell number/binucleation assay\",\n      \"journal\": \"ACS chemical biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — ATP-competitive mechanism established biochemically, phenotype confirmed by both pharmacological inhibition and genetic knockdown (two orthogonal methods)\",\n      \"pmids\": [\"27082499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"STK16 localizes to the Golgi throughout the cell cycle and directly binds actin, regulating actin dynamics in a concentration- and kinase activity-dependent manner. STK16 knockdown or kinase inhibition disrupts actin polymers, causes Golgi fragmentation, delays mitotic entry, prolongs mitosis, and causes prometaphase and cytokinesis arrest.\",\n      \"method\": \"In vitro actin-binding assay, siRNA knockdown, pharmacological kinase inhibition, live-cell imaging, immunofluorescence\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — direct actin binding established in vitro; loss-of-function phenotypes confirmed by both genetic knockdown and pharmacological inhibition, multiple readouts\",\n      \"pmids\": [\"28294156\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"STK16 autophosphorylates at Thr185, Ser197, and Tyr198 within its activation segment. Mutation of Tyr198 alone significantly reduces kinase activity, abolishes Golgi and membrane localization, and impairs cell cycle progression, identifying Tyr198 as the essential autophosphorylation site for STK16 localization and function.\",\n      \"method\": \"Site-directed mutagenesis of autophosphorylation sites, in vitro kinase assay, subcellular localization studies (immunofluorescence/fractionation), cell cycle analysis\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — mutagenesis combined with in vitro kinase assay and localization studies establishing mechanistic link between specific phosphorylation site and kinase function\",\n      \"pmids\": [\"31574902\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"STK16 directly phosphorylates c-MYC at serine 452, which prevents c-MYC degradation via the ubiquitin-proteasome pathway. Colorectal cancer cell proliferation driven by STK16 depends on this phosphorylation event. STK16 knockout or pharmacological inhibition reduces c-MYC protein levels and curtails tumor growth in vivo.\",\n      \"method\": \"Immunoprecipitation, immunoblot (phospho-specific), in vitro kinase assay, site-directed mutagenesis (S452), ubiquitination assay, cell proliferation assays, in vivo animal model with STK16 KO/inhibitor\",\n      \"journal\": \"Molecular medicine (Cambridge, Mass.)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — c-MYC S452 phosphorylation established by immunoprecipitation and functional rescue, but single lab and abstract-level description of methods without full mechanistic reconstitution\",\n      \"pmids\": [\"38622518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"STK16 knockdown inhibits LUAD cell proliferation and promotes apoptosis via the AKT1 pathway. STK16 is a transcriptional target of ETS1; miR-181a-5p (delivered via M1 macrophage exosomes) suppresses ETS1, thereby reducing STK16 expression and promoting apoptosis.\",\n      \"method\": \"siRNA knockdown, CCK-8 proliferation assay, apoptosis assay, luciferase reporter assay, ChIP assay, Western blotting, mouse xenograft model\",\n      \"journal\": \"Cancer science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2–3 / Moderate — loss-of-function phenotype with AKT1 pathway readout; ChIP assay links ETS1 to STK16 transcription; single lab with multiple methods but primarily upstream regulatory finding\",\n      \"pmids\": [\"35092121\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"STK16 is a myristoylated and palmitoylated serine/threonine kinase constitutively localized to the Golgi (dependent on autophosphorylation at Tyr198), where it directly binds actin and regulates actin dynamics in a kinase-activity-dependent manner to maintain Golgi structure and support cell cycle progression through mitosis and cytokinesis; it also shuttles to the nucleus upon Golgi disruption or overexpression, interacts with GlcNAcK (which allosterically enhances its kinase activity), phosphorylates c-MYC at Ser452 to protect it from proteasomal degradation, and its activity is required for VEGF secretion and smooth muscle contraction downstream of non-adrenergic stimuli.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"STK16 is an intrinsically active serine/threonine protein kinase that links Golgi-associated actin dynamics to cell cycle progression and to control of oncogenic signaling [#0, #4]. It is constitutively localized to the Golgi apparatus throughout the cell cycle, where it directly binds actin and regulates actin polymer organization in a concentration- and kinase-activity-dependent manner; loss of STK16 by knockdown or kinase inhibition disrupts actin polymers, fragments the Golgi, delays mitotic entry, and produces prometaphase and cytokinesis arrest with accumulation of binucleated cells [#3, #4]. Golgi and membrane targeting depend on autophosphorylation within the activation segment, with Tyr198 being the essential site whose mutation reduces kinase activity, abolishes Golgi/membrane localization, and impairs cell cycle progression [#5]. Upon Golgi disorganization or overexpression, STK16 translocates to the nucleus independently of its catalytic activity [#2]. Its kinase activity is enhanced by physical interaction with N-acetylglucosamine kinase (GlcNAcK), which binds STK16 but is not itself a substrate [#1]. STK16 also drives proliferative signaling: it directly phosphorylates c-MYC at Ser452 to protect c-MYC from ubiquitin-proteasome degradation, supporting colorectal cancer growth [#6], and its overexpression enhances VEGF production and secretion and increases tumor vascularity [#2]. Highly selective ATP-competitive inhibition phenocopies genetic loss, establishing that the kinase activity is required for these functions [#3].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Establishing that STK16/PKL12 is a bona fide catalytically active kinase was the founding question, settled by showing it phosphorylates substrate and autophosphorylates in isolation.\",\n      \"evidence\": \"In vitro kinase assay with bacterially purified recombinant protein, enolase substrate and autophosphorylation\",\n      \"pmids\": [\"9712705\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No physiological substrate identified\", \"No cellular localization or pathway context established\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Identifying a binding partner that modulates activity addressed how STK16 catalysis is regulated, showing GlcNAcK binds and allosterically enhances kinase activity without being a substrate.\",\n      \"evidence\": \"Yeast two-hybrid screen, in vitro pulldown, in vivo co-localization in vesicular structures, in vitro kinase assay\",\n      \"pmids\": [\"11741987\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism by which GlcNAcK enhances activity not resolved\", \"Physiological relevance of the interaction not tested in loss-of-function context\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Defining where STK16 acts addressed its compartmental role, establishing constitutive Golgi localization with kinase-independent nuclear translocation upon Golgi disruption, and linking it to VEGF secretion.\",\n      \"evidence\": \"Immunofluorescence, subcellular fractionation, kinase-dead E202A mutant, retroviral overexpression, in vivo xenograft\",\n      \"pmids\": [\"16310770\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Functional consequence of nuclear pool unknown\", \"Mechanism linking STK16 to VEGF secretion not defined\", \"Golgi-targeting determinants not identified\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"A selective ATP-competitive inhibitor (STK16-IN-1) addressed whether catalytic activity itself drives the cell division phenotype, showing pharmacological inhibition phenocopies RNAi knockdown.\",\n      \"evidence\": \"Biochemical kinase inhibition, KinomeScan selectivity profiling, RNAi knockdown, binucleation/cell number assays in MCF-7\",\n      \"pmids\": [\"27082499\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Relevant phosphorylation substrate for cell division not identified\", \"Mechanism producing binucleation not resolved\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Connecting STK16 to a direct molecular target addressed how it controls Golgi and mitosis, showing direct actin binding and kinase-activity-dependent regulation of actin dynamics underlying Golgi integrity and mitotic progression.\",\n      \"evidence\": \"In vitro actin-binding assay, siRNA knockdown, pharmacological inhibition, live-cell imaging, immunofluorescence\",\n      \"pmids\": [\"28294156\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether actin is a phosphorylation substrate not established\", \"Molecular link between actin regulation and cytokinesis arrest unresolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Mapping the activation-segment autophosphorylation sites addressed how STK16 activity and localization are coupled, identifying Tyr198 as the essential site for both kinase activity and Golgi/membrane targeting.\",\n      \"evidence\": \"Site-directed mutagenesis of Thr185/Ser197/Tyr198, in vitro kinase assay, localization studies, cell cycle analysis\",\n      \"pmids\": [\"31574902\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Upstream trigger of activation-segment autophosphorylation unknown\", \"How Tyr198 phosphorylation drives membrane association mechanistically unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Placing STK16 in a regulatory and survival circuit addressed its role in lung cancer, showing it acts via the AKT1 pathway and is transcriptionally controlled by ETS1 under miR-181a-5p regulation.\",\n      \"evidence\": \"siRNA knockdown, proliferation/apoptosis assays, luciferase reporter, ChIP, Western blot, mouse xenograft\",\n      \"pmids\": [\"35092121\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct STK16 substrate in the AKT1 axis not identified\", \"Whether STK16 acts upstream or in parallel to AKT1 not resolved\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Identifying a direct phosphosubstrate addressed how STK16 promotes tumor growth, showing it phosphorylates c-MYC at Ser452 to block proteasomal degradation in colorectal cancer.\",\n      \"evidence\": \"Immunoprecipitation, phospho-specific immunoblot, in vitro kinase assay, S452 mutagenesis, ubiquitination assay, STK16 KO/inhibitor in vivo\",\n      \"pmids\": [\"38622518\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single-lab finding without full mechanistic reconstitution\", \"How Golgi-localized STK16 accesses c-MYC not addressed\", \"Generality beyond colorectal context untested\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How STK16's Golgi/actin role mechanistically integrates with its substrate phosphorylation events (c-MYC, AKT1 axis) and VEGF secretion into a single signaling logic remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified substrate map linking Golgi actin regulation to nuclear/oncogenic targets\", \"Physiological upstream activators of STK16 unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 6]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [3]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [2, 4, 5]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [2]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [5]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [3, 4]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [6, 7]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"NAGK\", \"ACTB\", \"MYC\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":7,"faith_total":7,"faith_pct":100.0}}