{"gene":"CDK20","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2006,"finding":"PNQALRE/CCRK/CDK20 has no intrinsic CDK-activating kinase (CAK) activity as a monomer; it does not phosphorylate Cdk2 T-loop in vitro or in vivo, and its depletion by RNAi does not reduce Cdk2 T-loop phosphorylation or CAK activity of cell extracts. Instead, CDK7 is confirmed as the sole mammalian CAK. CDK20 knockdown impairs cell proliferation and increases apoptosis (sub-G1 DNA content, PARP cleavage) without discrete cell-cycle arrest.","method":"RNAi knockdown, in vitro CAK assay, in vivo T-loop phosphorylation measurement, PARP cleavage assay, flow cytometry","journal":"Cell cycle (Georgetown, Tex.)","confidence":"High","confidence_rationale":"Tier 1–2 / Moderate — in vitro kinase assay plus in vivo phosphorylation measurement and cell-extract CAK activity, single lab with multiple orthogonal methods","pmids":["16552187"],"is_preprint":false},{"year":2013,"finding":"CCRK/CDK20 and its substrate ICK inhibit ciliogenesis; CCRK depletion causes accumulation of ICK at ciliary tips, altered intraflagellar transport (IFT), and inhibition of cell cycle re-entry. In glioblastoma cells with high CCRK, its depletion restores primary cilia through ICK and the ICK-related kinase MAK, thereby inhibiting glioblastoma cell proliferation.","method":"RNAi knockdown, immunofluorescence, live-cell imaging of ciliary tip ICK accumulation, cell proliferation assays in NIH3T3 and glioblastoma cells","journal":"EMBO reports","confidence":"High","confidence_rationale":"Tier 2 / Moderate — clean KD with defined cellular phenotype (ciliogenesis, IFT, proliferation), multiple cell models, substrate-kinase cascade established","pmids":["23743448"],"is_preprint":false},{"year":2017,"finding":"CCRK/CDK20 activates NF-κB via EZH2 and facilitates NF-κB–EZH2 co-binding to the IL-6 promoter, driving immunosuppressive MDSC expansion in hepatocellular carcinoma. This CCRK→EZH2/NF-κB→IL-6 cascade promotes T-cell suppression.","method":"CRISPR/Cas9 Ccrk depletion, liver-specific transgenic mice, ChIP showing NF-κB–EZH2 co-occupancy at IL-6 promoter, flow cytometry, co-culture immunosuppression assays, IL-6 trap rescue","journal":"Gut","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal genetic and biochemical evidence (transgenic gain, CRISPR loss, ChIP), replicated in patient samples and mouse models","pmids":["28939663"],"is_preprint":false},{"year":2017,"finding":"CDK20/CCRK binds directly to the ubiquitin ligase adaptor KEAP1 via an evolutionarily conserved ETGE motif on CDK20, competing with NRF2 for KEAP1 binding. This competition enhances NRF2 transcriptional activity, lowers cellular ROS, and confers radiochemoresistance in lung cancer cells.","method":"Tandem affinity purification, co-immunoprecipitation, ETGE-motif competition binding assays, CDK20 knockdown with NRF2 reporter assays, ROS measurement, clonogenic survival assays","journal":"Oncogene","confidence":"High","confidence_rationale":"Tier 2 / Moderate — TAP-based interaction identification plus functional rescue with NRF2, multiple orthogonal assays in single lab","pmids":["28534518"],"is_preprint":false},{"year":2017,"finding":"CCRK/CDK20 is required for proper Hedgehog (Hh) pathway signaling in mice; Ccrk mutant cells show defective ciliary length regulation, impaired intraflagellar transport, and slowed ciliary enrichment of Smoothened and Gli2. Genetic analyses place CCRK at the level of or downstream of Smoothened and upstream of Gli2/Gli3.","method":"Mouse knockout/mutant genetics, epistasis analyses, immunofluorescence of ciliary protein localization, IFT velocity measurements, in vitro Hh signaling assays","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Moderate — genetic epistasis in vivo plus cell biological localization with functional consequence, multiple orthogonal methods","pmids":["28817564"],"is_preprint":false},{"year":2018,"finding":"CCRK/CDK20 drives a feedforward signaling loop: it induces STAT3–AR promoter co-occupancy to transcriptionally upregulate AR, which in turn activates mTORC1/4E-BP1/S6K/SREBP1 cascades via GSK3β phosphorylation. Additionally, CCRK activates mTORC1-dependent G-csf expression to recruit immunosuppressive PMN-MDSCs.","method":"Lentiviral Ccrk ablation in diet-induced obese mice, transgenic hepatic CCRK induction, ChIP for STAT3–AR co-occupancy, phosphorylation assays for GSK3β and mTORC1 substrates, cytokine measurement","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic ablation and transgenic induction with ChIP and phospho-pathway readouts, replicated in multiple model systems","pmids":["30523261"],"is_preprint":false},{"year":2019,"finding":"In C. elegans, DYF-18/CCRK and DYF-5/MAK act in a kinase cascade to control cilia branching and length; loss of dyf-18 leads to elongated, unbranched cilia with increased tubulin load, reduced tubulin turnover, and EBP-2 decoration of axonemal microtubules along their lengths. Microtubule-destabilizing tubulin mutations and IFT tubulin-transport mutations suppress cilia elongation in dyf-18 mutants, placing CCRK upstream of MAK and upstream of axonemal microtubule stability.","method":"C. elegans genetics (dyf-18 null mutants), epistasis with tubulin and IFT mutants, live-cell IFT motor imaging, EBP-2 dynamics (FRAP/live imaging), fluorescence intensity measurements of tubulin load","journal":"Current biology : CB","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis across multiple alleles and tubulin mutants, live IFT imaging, orthogonal biochemical readouts","pmids":["30955935"],"is_preprint":false},{"year":2010,"finding":"CCRK/CDK20 is required for phosphorylation of CDK2 on Thr-160 and Rb on Ser-795 and for expression of cyclin E in colorectal cancer cells; its knockdown causes G1 phase arrest and reduced proliferation.","method":"siRNA and shRNA knockdown, Western blotting for CDK2-pThr160 and Rb-pSer795, flow cytometry cell cycle analysis, cell proliferation assays in LoVo and DLD1 cells","journal":"European journal of cancer (Oxford, England : 1990)","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — clean KD with phospho-substrate readouts, single lab, no in vitro kinase reconstitution to confirm direct phosphorylation","pmids":["20466538"],"is_preprint":false},{"year":2021,"finding":"CCRK/CDK20 interacts with BROMI/TBC1D32 and this interaction is required for regulating IFT turnaround at the ciliary tip; CCRK-KO cells show overaccumulation of IFT proteins at bulged ciliary tips, GPR161 and Smoothened enrichment on the ciliary membrane, and elimination of tip material as extracellular vesicles. Rescue requires both kinase activity and BROMI-binding competence of CCRK, and phenotypes resemble ICK-KO, placing CCRK upstream of ICK.","method":"CCRK-knockout cell generation, exogenous rescue with wild-type vs. kinase-dead and BROMI-binding mutants, immunofluorescence of IFT proteins and ciliary membrane receptors, extracellular vesicle analysis","journal":"PloS one","confidence":"High","confidence_rationale":"Tier 2 / Moderate — KO with domain-separation rescue mutants defining both kinase activity and BROMI interaction as required, multiple orthogonal phenotypic readouts","pmids":["34624068"],"is_preprint":false},{"year":2022,"finding":"CCRK/CDK20 interacts with BROMI/TBC1D32, FAM149B1/JBTS36, and CFAP20 to regulate IFT turnaround at the ciliary tip. BROMI mutants defective in CCRK binding cannot rescue BROMI-KO ciliary defects; CCRK-KO, BROMI-KO, and FAM149B1-KO cells show identical phenotypes including cilia elongation and IFT/ICK tip accumulation, indicating these proteins function together upstream of ICK.","method":"Co-immunoprecipitation (CCRK–BROMI, CCRK–FAM149B1, BROMI–FAM149B1, BROMI–CFAP20), KO cell generation, rescue with BROMI binding mutants, immunofluorescence","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP defining complex composition, KO phenotypes with domain-separation rescue, multiple labs converging on the same pathway","pmids":["35609210"],"is_preprint":false},{"year":2024,"finding":"CCRK kinase is an upstream activator of both MAK and ICK in retinal photoreceptor cells; the CCRK–MAK/ICK axis constitutes an IFT regulator essential for photoreceptor ciliary axoneme maintenance and retinal survival.","method":"Mouse Ccrk conditional knockout, retinal degeneration phenotyping, genetic epistasis with Mak and Ick mutants, IFT protein localization by immunofluorescence","journal":"Life science alliance","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — in vivo KO with defined photoreceptor phenotype and genetic epistasis, single study","pmids":["39293864"],"is_preprint":false},{"year":2025,"finding":"CDK20/LF2 phosphorylates the activation loop of CDKL5 (Chlamydomonas LF5), activating it; this phosphorylation controls CDKL5 ciliary localization, downregulates its IFT-mediated transport as flagella reach steady state, and influences flagellar length. Mouse Cdk20 is required for proper Cdkl5 localization within cilia, and Cdkl5 loss elongates cilia in a CDK20-dependent manner.","method":"Live-cell imaging, immunofluorescence, biochemical assays, mass spectrometry phosphorylation mapping, Chlamydomonas and mouse Cdk20-KO genetic analysis, reconstitution of kinase activation","journal":"PLoS biology","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct phosphorylation of CDKL5 activation loop identified by mass spectrometry plus genetic KO rescue in both Chlamydomonas and mouse, multiple orthogonal methods","pmids":["41385589"],"is_preprint":false},{"year":2025,"finding":"CCRK/CDK20 interacts with KU70, modulates its protein stability, and thereby enhances non-homologous end joining (NHEJ) DNA repair activity downstream of the AR–CCRK axis in breast cancer cells.","method":"Co-immunoprecipitation (CCRK–KU70), EJ5-GFP NHEJ reporter assay, CCRK knockdown/overexpression, ARE-luciferase AR activity assay, cell viability and comet assays","journal":"Cells","confidence":"Medium","confidence_rationale":"Tier 3 / Weak — single Co-IP for interaction, NHEJ reporter functional assay, single lab","pmids":["40940753"],"is_preprint":false},{"year":2011,"finding":"In C. elegans, the CDK/CCRK/LF2p-related kinase DYF-18 is required for proper intraflagellar transport function and ciliogenesis; dyf-18 mutants display dye-filling defects indicative of IFT disruption in ciliated sensory neurons.","method":"C. elegans mutant analysis (dye-filling assay), transcriptional GFP reporters for expression in ciliated sensory neurons, genetic epistasis with DAF-19 RFX targets","journal":"Developmental biology","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — defined in vivo phenotype in ortholog, single study, no direct biochemical mechanism for this isoform","pmids":["21740898"],"is_preprint":false}],"current_model":"CDK20 (CCRK/PNQALRE) is a serine/threonine kinase that functions as the master upstream activator of the ciliary kinase cascade (ICK/CILK1, MAK, and CDKL5) by phosphorylating their activation loops, thereby controlling intraflagellar transport turnaround at ciliary tips, ciliary length, and Hedgehog pathway signaling; it also competes with NRF2 for KEAP1 binding via an ETGE motif to activate the NRF2 cytoprotective pathway, drives oncogenic EZH2/NF-κB/IL-6 and STAT3-AR-mTORC1 signaling circuits in cancer, and stabilizes KU70 to promote DNA repair, while its previously proposed CAK activity toward CDK2 has been experimentally refuted."},"narrative":{"mechanistic_narrative":"CDK20 (CCRK) is a serine/threonine protein kinase that functions as the master upstream activator of a ciliary kinase cascade controlling intraflagellar transport (IFT) turnaround, ciliary length, and Hedgehog signaling [PMID:23743448, PMID:28817564, PMID:41385589]. It activates the related kinases ICK/CILK1, MAK, and CDKL5 by phosphorylating their activation loops—a mechanism demonstrated directly for CDKL5, whose activation-loop phosphorylation by CDK20 was mapped by mass spectrometry and controls CDKL5 ciliary localization and flagellar length across Chlamydomonas and mouse [PMID:41385589]—and acts upstream of MAK and ICK in photoreceptor axoneme maintenance and retinal survival [PMID:39293864]. At the ciliary tip, CDK20 operates within a complex with BROMI/TBC1D32, FAM149B1, and CFAP20 to govern IFT turnaround; loss of CDK20 causes overaccumulation of IFT proteins at bulged tips, aberrant ciliary enrichment of GPR161 and Smoothened, and excessive tip-derived extracellular vesicles, with rescue requiring both its kinase activity and BROMI-binding competence [PMID:34624068, PMID:35609210]. CDK20 is required for proper Hedgehog pathway output, acting at or downstream of Smoothened and upstream of Gli2/Gli3 [PMID:28817564]. Beyond cilia, CDK20 drives oncogenic signaling circuits, including an EZH2/NF-κB/IL-6 cascade promoting immunosuppression in hepatocellular carcinoma [PMID:28939663] and a STAT3–AR–mTORC1 feedforward loop [PMID:30523261], competes with NRF2 for KEAP1 binding via an ETGE motif to activate the NRF2 cytoprotective program [PMID:28534518], and stabilizes KU70 to promote NHEJ repair [PMID:40940753]. Its previously proposed CDK-activating kinase (CAK) activity toward CDK2 has been experimentally refuted, with CDK7 confirmed as the sole mammalian CAK [PMID:16552187].","teleology":[{"year":2006,"claim":"Resolved whether CDK20 is a CDK-activating kinase: it has no intrinsic CAK activity and does not phosphorylate the CDK2 T-loop, redirecting the field away from a cell-cycle CAK role.","evidence":"RNAi knockdown with in vitro CAK assay, in vivo T-loop phosphorylation, PARP cleavage and flow cytometry in mammalian cells","pmids":["16552187"],"confidence":"High","gaps":["Did not identify the bona fide substrates or activating partners of CDK20","Proliferation/apoptosis phenotype mechanism left undefined"]},{"year":2010,"claim":"Tested CDK20's role in cell-cycle progression in cancer cells, linking it to CDK2/Rb phosphorylation and cyclin E expression with G1 arrest upon loss.","evidence":"siRNA/shRNA knockdown with phospho-Western (CDK2-pThr160, Rb-pSer795) and cell-cycle analysis in colorectal cancer lines","pmids":["20466538"],"confidence":"Medium","gaps":["No in vitro kinase reconstitution to confirm direct phosphorylation","Apparent tension with the 2006 refutation of CAK activity not reconciled"]},{"year":2013,"claim":"Established CDK20 as a regulator of ciliogenesis via the substrate kinase ICK and the related MAK, linking ciliary control to glioblastoma proliferation.","evidence":"RNAi knockdown, immunofluorescence and live-cell imaging of ciliary tip ICK, proliferation assays in NIH3T3 and glioblastoma cells","pmids":["23743448"],"confidence":"High","gaps":["Direct phosphorylation of ICK by CDK20 not biochemically mapped here","Mechanism connecting ciliary control to proliferation incompletely defined"]},{"year":2017,"claim":"Defined three distinct CDK20 effector arms—Hedgehog/ciliary IFT, KEAP1/NRF2 cytoprotection, and EZH2/NF-κB/IL-6 immunosuppression—broadening its role beyond cilia into oncogenic and redox signaling.","evidence":"Mouse mutant genetics with Hh epistasis and ciliary localization (PLoS Genet); TAP/Co-IP with ETGE-motif competition and NRF2 reporters (Oncogene); CRISPR/transgenic mice with ChIP and immunosuppression assays (Gut)","pmids":["28817564","28534518","28939663"],"confidence":"High","gaps":["Whether KEAP1 binding and kinase activity are mechanistically coupled is unresolved","Direct kinase substrates within the NF-κB/EZH2 arm not identified"]},{"year":2018,"claim":"Mapped a STAT3–AR–mTORC1 feedforward circuit downstream of CDK20 driving metabolic-oncogenic signaling and MDSC recruitment.","evidence":"Lentiviral ablation and transgenic hepatic induction in mice, ChIP for STAT3–AR co-occupancy, phospho-pathway readouts (GSK3β, mTORC1 substrates)","pmids":["30523261"],"confidence":"High","gaps":["Direct kinase target initiating the loop not pinpointed","Connection between this circuit and the ciliary kinase function unexplored"]},{"year":2019,"claim":"Placed CDK20 (DYF-18) genetically upstream of MAK (DYF-5) and upstream of axonemal microtubule stability, mechanistically linking the cascade to tubulin turnover and cilia length/branching.","evidence":"C. elegans genetics with tubulin and IFT mutant epistasis, live IFT motor imaging, EBP-2 dynamics","pmids":["30955935"],"confidence":"High","gaps":["Biochemical demonstration of DYF-5 activation-loop phosphorylation not shown in this system","Generalization to mammalian axonemes inferred, not directly tested"]},{"year":2021,"claim":"Showed CDK20 requires both kinase activity and BROMI/TBC1D32 binding to control IFT turnaround at the ciliary tip, situating it upstream of ICK with ICK-like KO phenotypes.","evidence":"CCRK-KO cells with WT vs. kinase-dead and BROMI-binding mutant rescue, IFT/membrane receptor immunofluorescence, extracellular vesicle analysis","pmids":["34624068"],"confidence":"High","gaps":["Whether BROMI is a substrate or a scaffold for substrate presentation unclear","Direct phosphorylation event at the tip not biochemically captured"]},{"year":2022,"claim":"Defined the multi-protein tip complex (CDK20–BROMI–FAM149B1–CFAP20) acting together upstream of ICK, since KO of each component produced identical ciliary defects.","evidence":"Reciprocal Co-IP defining complex composition, KO cells with BROMI-binding mutant rescue, immunofluorescence","pmids":["35609210"],"confidence":"High","gaps":["Stoichiometry and order of assembly of the complex not resolved","Catalytic substrate(s) within the complex not identified"]},{"year":2024,"claim":"Extended the CDK20–MAK/ICK axis to photoreceptor ciliary maintenance, establishing physiological relevance for retinal survival.","evidence":"Mouse Ccrk conditional KO with retinal degeneration phenotyping, epistasis with Mak/Ick, IFT immunofluorescence","pmids":["39293864"],"confidence":"Medium","gaps":["Single study","Direct activation-loop phosphorylation of MAK/ICK in photoreceptors not biochemically shown"]},{"year":2025,"claim":"Provided direct biochemical proof that CDK20 phosphorylates the CDKL5 activation loop to activate it and control its ciliary transport and flagellar length, completing the mechanistic logic of the cascade; also implicated CDK20 in KU70 stabilization and NHEJ.","evidence":"MS phosphorylation mapping and kinase-activation reconstitution in Chlamydomonas with Cdk20-KO rescue in mouse (PLoS Biol); Co-IP, EJ5-GFP NHEJ reporter and AR-luciferase in breast cancer cells (Cells)","pmids":["41385589","40940753"],"confidence":"High","gaps":["KU70 interaction rests on single Co-IP without reciprocal validation","Whether KU70 stabilization requires CDK20 catalytic activity not established"]},{"year":null,"claim":"How CDK20 itself is activated and regulated, and how its ciliary kinase function mechanistically integrates with its oncogenic NRF2/NF-κB/STAT3-AR and DNA-repair roles, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No identified activating cyclin/partner or upstream regulator of CDK20 catalytic activity","No structural model linking kinase, ETGE, and BROMI-binding functions","Whether oncogenic circuits depend on ciliary cascade substrates is untested"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[11,8,7]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[11,8]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[3,12]}],"localization":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[1,4,8,9,11]}],"pathway":[{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[4]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[4,2,5]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[4,10]},{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[3]},{"term_id":"R-HSA-73894","term_label":"DNA Repair","supporting_discovery_ids":[12]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[2,5]}],"complexes":["CDK20–BROMI(TBC1D32)–FAM149B1–CFAP20 ciliary tip complex"],"partners":["ICK/CILK1","MAK","CDKL5","BROMI/TBC1D32","FAM149B1","KEAP1","KU70","CFAP20"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8IZL9","full_name":"Cyclin-dependent kinase 20","aliases":["CDK-activating kinase p42","CAK-kinase p42","Cell cycle-related kinase","Cell division protein kinase 20","Cyclin-dependent protein kinase H","Cyclin-kinase-activating kinase p42"],"length_aa":346,"mass_kda":38.7,"function":"Required for high-level Shh responses in the developing neural tube. Together with TBC1D32, controls the structure of the primary cilium by coordinating assembly of the ciliary membrane and axoneme, allowing GLI2 to be properly activated in response to SHH signaling (By similarity). Involved in cell growth. Activates CDK2, a kinase involved in the control of the cell cycle, by phosphorylating residue 'Thr-160'","subcellular_location":"Nucleus; Cytoplasm; Cell projection, cilium","url":"https://www.uniprot.org/uniprotkb/Q8IZL9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CDK20","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CDK20","total_profiled":1310},"omim":[{"mim_id":"615867","title":"TBC1 DOMAIN FAMILY, MEMBER 32; TBC1D32","url":"https://www.omim.org/entry/615867"},{"mim_id":"610076","title":"CYCLIN-DEPENDENT KINASE 20; CDK20","url":"https://www.omim.org/entry/610076"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Golgi apparatus","reliability":"Additional"},{"location":"Connecting piece","reliability":"Additional"},{"location":"Mid piece","reliability":"Additional"},{"location":"Principal piece","reliability":"Additional"},{"location":"End piece","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/CDK20"},"hgnc":{"alias_symbol":["p42","PNQALRE"],"prev_symbol":["CCRK"]},"alphafold":{"accession":"Q8IZL9","domains":[{"cath_id":"3.30.200.20","chopping":"5-84_306-335","consensus_level":"high","plddt":72.7507,"start":5,"end":335},{"cath_id":"1.10.510.10","chopping":"88-300","consensus_level":"high","plddt":92.6392,"start":88,"end":300}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IZL9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IZL9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8IZL9-F1-predicted_aligned_error_v6.png","plddt_mean":85.88},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CDK20","jax_strain_url":"https://www.jax.org/strain/search?query=CDK20"},"sequence":{"accession":"Q8IZL9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8IZL9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8IZL9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8IZL9"}},"corpus_meta":[{"pmid":"8194526","id":"PMC_8194526","title":"c-Abl 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The Model of Encounter Complex Involving the Double Mutant of the c-Crk N-SH3 Domain and Peptide Sos.","date":"2016","source":"Biochemistry","url":"https://pubmed.ncbi.nlm.nih.gov/26910732","citation_count":15,"is_preprint":false},{"pmid":"35609210","id":"PMC_35609210","title":"BROMI/TBC1D32 together with CCRK/CDK20 and FAM149B1/JBTS36 contributes to intraflagellar transport turnaround involving ICK/CILK1.","date":"2022","source":"Molecular biology of the cell","url":"https://pubmed.ncbi.nlm.nih.gov/35609210","citation_count":12,"is_preprint":false},{"pmid":"21336985","id":"PMC_21336985","title":"c-Crk proto-oncogene contributes to transcriptional repression of p120-catenin in non-small cell lung cancer cells.","date":"2011","source":"Clinical & experimental metastasis","url":"https://pubmed.ncbi.nlm.nih.gov/21336985","citation_count":12,"is_preprint":false},{"pmid":"34624068","id":"PMC_34624068","title":"CCRK/CDK20 regulates ciliary retrograde protein trafficking via interacting with 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molecular & cellular mechanisms","url":"https://pubmed.ncbi.nlm.nih.gov/41618774","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":24497,"output_tokens":4035,"usd":0.067008,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":11790,"output_tokens":4084,"usd":0.080525,"stage2_stop_reason":"end_turn"},"total_usd":0.147533,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2006,\n      \"finding\": \"PNQALRE/CCRK/CDK20 has no intrinsic CDK-activating kinase (CAK) activity as a monomer; it does not phosphorylate Cdk2 T-loop in vitro or in vivo, and its depletion by RNAi does not reduce Cdk2 T-loop phosphorylation or CAK activity of cell extracts. Instead, CDK7 is confirmed as the sole mammalian CAK. CDK20 knockdown impairs cell proliferation and increases apoptosis (sub-G1 DNA content, PARP cleavage) without discrete cell-cycle arrest.\",\n      \"method\": \"RNAi knockdown, in vitro CAK assay, in vivo T-loop phosphorylation measurement, PARP cleavage assay, flow cytometry\",\n      \"journal\": \"Cell cycle (Georgetown, Tex.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 / Moderate — in vitro kinase assay plus in vivo phosphorylation measurement and cell-extract CAK activity, single lab with multiple orthogonal methods\",\n      \"pmids\": [\"16552187\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"CCRK/CDK20 and its substrate ICK inhibit ciliogenesis; CCRK depletion causes accumulation of ICK at ciliary tips, altered intraflagellar transport (IFT), and inhibition of cell cycle re-entry. In glioblastoma cells with high CCRK, its depletion restores primary cilia through ICK and the ICK-related kinase MAK, thereby inhibiting glioblastoma cell proliferation.\",\n      \"method\": \"RNAi knockdown, immunofluorescence, live-cell imaging of ciliary tip ICK accumulation, cell proliferation assays in NIH3T3 and glioblastoma cells\",\n      \"journal\": \"EMBO reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — clean KD with defined cellular phenotype (ciliogenesis, IFT, proliferation), multiple cell models, substrate-kinase cascade established\",\n      \"pmids\": [\"23743448\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CCRK/CDK20 activates NF-κB via EZH2 and facilitates NF-κB–EZH2 co-binding to the IL-6 promoter, driving immunosuppressive MDSC expansion in hepatocellular carcinoma. This CCRK→EZH2/NF-κB→IL-6 cascade promotes T-cell suppression.\",\n      \"method\": \"CRISPR/Cas9 Ccrk depletion, liver-specific transgenic mice, ChIP showing NF-κB–EZH2 co-occupancy at IL-6 promoter, flow cytometry, co-culture immunosuppression assays, IL-6 trap rescue\",\n      \"journal\": \"Gut\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal genetic and biochemical evidence (transgenic gain, CRISPR loss, ChIP), replicated in patient samples and mouse models\",\n      \"pmids\": [\"28939663\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CDK20/CCRK binds directly to the ubiquitin ligase adaptor KEAP1 via an evolutionarily conserved ETGE motif on CDK20, competing with NRF2 for KEAP1 binding. This competition enhances NRF2 transcriptional activity, lowers cellular ROS, and confers radiochemoresistance in lung cancer cells.\",\n      \"method\": \"Tandem affinity purification, co-immunoprecipitation, ETGE-motif competition binding assays, CDK20 knockdown with NRF2 reporter assays, ROS measurement, clonogenic survival assays\",\n      \"journal\": \"Oncogene\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — TAP-based interaction identification plus functional rescue with NRF2, multiple orthogonal assays in single lab\",\n      \"pmids\": [\"28534518\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"CCRK/CDK20 is required for proper Hedgehog (Hh) pathway signaling in mice; Ccrk mutant cells show defective ciliary length regulation, impaired intraflagellar transport, and slowed ciliary enrichment of Smoothened and Gli2. Genetic analyses place CCRK at the level of or downstream of Smoothened and upstream of Gli2/Gli3.\",\n      \"method\": \"Mouse knockout/mutant genetics, epistasis analyses, immunofluorescence of ciliary protein localization, IFT velocity measurements, in vitro Hh signaling assays\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis in vivo plus cell biological localization with functional consequence, multiple orthogonal methods\",\n      \"pmids\": [\"28817564\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CCRK/CDK20 drives a feedforward signaling loop: it induces STAT3–AR promoter co-occupancy to transcriptionally upregulate AR, which in turn activates mTORC1/4E-BP1/S6K/SREBP1 cascades via GSK3β phosphorylation. Additionally, CCRK activates mTORC1-dependent G-csf expression to recruit immunosuppressive PMN-MDSCs.\",\n      \"method\": \"Lentiviral Ccrk ablation in diet-induced obese mice, transgenic hepatic CCRK induction, ChIP for STAT3–AR co-occupancy, phosphorylation assays for GSK3β and mTORC1 substrates, cytokine measurement\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic ablation and transgenic induction with ChIP and phospho-pathway readouts, replicated in multiple model systems\",\n      \"pmids\": [\"30523261\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In C. elegans, DYF-18/CCRK and DYF-5/MAK act in a kinase cascade to control cilia branching and length; loss of dyf-18 leads to elongated, unbranched cilia with increased tubulin load, reduced tubulin turnover, and EBP-2 decoration of axonemal microtubules along their lengths. Microtubule-destabilizing tubulin mutations and IFT tubulin-transport mutations suppress cilia elongation in dyf-18 mutants, placing CCRK upstream of MAK and upstream of axonemal microtubule stability.\",\n      \"method\": \"C. elegans genetics (dyf-18 null mutants), epistasis with tubulin and IFT mutants, live-cell IFT motor imaging, EBP-2 dynamics (FRAP/live imaging), fluorescence intensity measurements of tubulin load\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis across multiple alleles and tubulin mutants, live IFT imaging, orthogonal biochemical readouts\",\n      \"pmids\": [\"30955935\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"CCRK/CDK20 is required for phosphorylation of CDK2 on Thr-160 and Rb on Ser-795 and for expression of cyclin E in colorectal cancer cells; its knockdown causes G1 phase arrest and reduced proliferation.\",\n      \"method\": \"siRNA and shRNA knockdown, Western blotting for CDK2-pThr160 and Rb-pSer795, flow cytometry cell cycle analysis, cell proliferation assays in LoVo and DLD1 cells\",\n      \"journal\": \"European journal of cancer (Oxford, England : 1990)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — clean KD with phospho-substrate readouts, single lab, no in vitro kinase reconstitution to confirm direct phosphorylation\",\n      \"pmids\": [\"20466538\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"CCRK/CDK20 interacts with BROMI/TBC1D32 and this interaction is required for regulating IFT turnaround at the ciliary tip; CCRK-KO cells show overaccumulation of IFT proteins at bulged ciliary tips, GPR161 and Smoothened enrichment on the ciliary membrane, and elimination of tip material as extracellular vesicles. Rescue requires both kinase activity and BROMI-binding competence of CCRK, and phenotypes resemble ICK-KO, placing CCRK upstream of ICK.\",\n      \"method\": \"CCRK-knockout cell generation, exogenous rescue with wild-type vs. kinase-dead and BROMI-binding mutants, immunofluorescence of IFT proteins and ciliary membrane receptors, extracellular vesicle analysis\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO with domain-separation rescue mutants defining both kinase activity and BROMI interaction as required, multiple orthogonal phenotypic readouts\",\n      \"pmids\": [\"34624068\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"CCRK/CDK20 interacts with BROMI/TBC1D32, FAM149B1/JBTS36, and CFAP20 to regulate IFT turnaround at the ciliary tip. BROMI mutants defective in CCRK binding cannot rescue BROMI-KO ciliary defects; CCRK-KO, BROMI-KO, and FAM149B1-KO cells show identical phenotypes including cilia elongation and IFT/ICK tip accumulation, indicating these proteins function together upstream of ICK.\",\n      \"method\": \"Co-immunoprecipitation (CCRK–BROMI, CCRK–FAM149B1, BROMI–FAM149B1, BROMI–CFAP20), KO cell generation, rescue with BROMI binding mutants, immunofluorescence\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP defining complex composition, KO phenotypes with domain-separation rescue, multiple labs converging on the same pathway\",\n      \"pmids\": [\"35609210\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"CCRK kinase is an upstream activator of both MAK and ICK in retinal photoreceptor cells; the CCRK–MAK/ICK axis constitutes an IFT regulator essential for photoreceptor ciliary axoneme maintenance and retinal survival.\",\n      \"method\": \"Mouse Ccrk conditional knockout, retinal degeneration phenotyping, genetic epistasis with Mak and Ick mutants, IFT protein localization by immunofluorescence\",\n      \"journal\": \"Life science alliance\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — in vivo KO with defined photoreceptor phenotype and genetic epistasis, single study\",\n      \"pmids\": [\"39293864\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CDK20/LF2 phosphorylates the activation loop of CDKL5 (Chlamydomonas LF5), activating it; this phosphorylation controls CDKL5 ciliary localization, downregulates its IFT-mediated transport as flagella reach steady state, and influences flagellar length. Mouse Cdk20 is required for proper Cdkl5 localization within cilia, and Cdkl5 loss elongates cilia in a CDK20-dependent manner.\",\n      \"method\": \"Live-cell imaging, immunofluorescence, biochemical assays, mass spectrometry phosphorylation mapping, Chlamydomonas and mouse Cdk20-KO genetic analysis, reconstitution of kinase activation\",\n      \"journal\": \"PLoS biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct phosphorylation of CDKL5 activation loop identified by mass spectrometry plus genetic KO rescue in both Chlamydomonas and mouse, multiple orthogonal methods\",\n      \"pmids\": [\"41385589\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"CCRK/CDK20 interacts with KU70, modulates its protein stability, and thereby enhances non-homologous end joining (NHEJ) DNA repair activity downstream of the AR–CCRK axis in breast cancer cells.\",\n      \"method\": \"Co-immunoprecipitation (CCRK–KU70), EJ5-GFP NHEJ reporter assay, CCRK knockdown/overexpression, ARE-luciferase AR activity assay, cell viability and comet assays\",\n      \"journal\": \"Cells\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single Co-IP for interaction, NHEJ reporter functional assay, single lab\",\n      \"pmids\": [\"40940753\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"In C. elegans, the CDK/CCRK/LF2p-related kinase DYF-18 is required for proper intraflagellar transport function and ciliogenesis; dyf-18 mutants display dye-filling defects indicative of IFT disruption in ciliated sensory neurons.\",\n      \"method\": \"C. elegans mutant analysis (dye-filling assay), transcriptional GFP reporters for expression in ciliated sensory neurons, genetic epistasis with DAF-19 RFX targets\",\n      \"journal\": \"Developmental biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — defined in vivo phenotype in ortholog, single study, no direct biochemical mechanism for this isoform\",\n      \"pmids\": [\"21740898\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CDK20 (CCRK/PNQALRE) is a serine/threonine kinase that functions as the master upstream activator of the ciliary kinase cascade (ICK/CILK1, MAK, and CDKL5) by phosphorylating their activation loops, thereby controlling intraflagellar transport turnaround at ciliary tips, ciliary length, and Hedgehog pathway signaling; it also competes with NRF2 for KEAP1 binding via an ETGE motif to activate the NRF2 cytoprotective pathway, drives oncogenic EZH2/NF-κB/IL-6 and STAT3-AR-mTORC1 signaling circuits in cancer, and stabilizes KU70 to promote DNA repair, while its previously proposed CAK activity toward CDK2 has been experimentally refuted.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CDK20 (CCRK) is a serine/threonine protein kinase that functions as the master upstream activator of a ciliary kinase cascade controlling intraflagellar transport (IFT) turnaround, ciliary length, and Hedgehog signaling [#1, #4, #11]. It activates the related kinases ICK/CILK1, MAK, and CDKL5 by phosphorylating their activation loops—a mechanism demonstrated directly for CDKL5, whose activation-loop phosphorylation by CDK20 was mapped by mass spectrometry and controls CDKL5 ciliary localization and flagellar length across Chlamydomonas and mouse [#11]—and acts upstream of MAK and ICK in photoreceptor axoneme maintenance and retinal survival [#10]. At the ciliary tip, CDK20 operates within a complex with BROMI/TBC1D32, FAM149B1, and CFAP20 to govern IFT turnaround; loss of CDK20 causes overaccumulation of IFT proteins at bulged tips, aberrant ciliary enrichment of GPR161 and Smoothened, and excessive tip-derived extracellular vesicles, with rescue requiring both its kinase activity and BROMI-binding competence [#8, #9]. CDK20 is required for proper Hedgehog pathway output, acting at or downstream of Smoothened and upstream of Gli2/Gli3 [#4]. Beyond cilia, CDK20 drives oncogenic signaling circuits, including an EZH2/NF-κB/IL-6 cascade promoting immunosuppression in hepatocellular carcinoma [#2] and a STAT3–AR–mTORC1 feedforward loop [#5], competes with NRF2 for KEAP1 binding via an ETGE motif to activate the NRF2 cytoprotective program [#3], and stabilizes KU70 to promote NHEJ repair [#12]. Its previously proposed CDK-activating kinase (CAK) activity toward CDK2 has been experimentally refuted, with CDK7 confirmed as the sole mammalian CAK [#0].\",\n  \"teleology\": [\n    {\n      \"year\": 2006,\n      \"claim\": \"Resolved whether CDK20 is a CDK-activating kinase: it has no intrinsic CAK activity and does not phosphorylate the CDK2 T-loop, redirecting the field away from a cell-cycle CAK role.\",\n      \"evidence\": \"RNAi knockdown with in vitro CAK assay, in vivo T-loop phosphorylation, PARP cleavage and flow cytometry in mammalian cells\",\n      \"pmids\": [\"16552187\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not identify the bona fide substrates or activating partners of CDK20\", \"Proliferation/apoptosis phenotype mechanism left undefined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Tested CDK20's role in cell-cycle progression in cancer cells, linking it to CDK2/Rb phosphorylation and cyclin E expression with G1 arrest upon loss.\",\n      \"evidence\": \"siRNA/shRNA knockdown with phospho-Western (CDK2-pThr160, Rb-pSer795) and cell-cycle analysis in colorectal cancer lines\",\n      \"pmids\": [\"20466538\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No in vitro kinase reconstitution to confirm direct phosphorylation\", \"Apparent tension with the 2006 refutation of CAK activity not reconciled\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Established CDK20 as a regulator of ciliogenesis via the substrate kinase ICK and the related MAK, linking ciliary control to glioblastoma proliferation.\",\n      \"evidence\": \"RNAi knockdown, immunofluorescence and live-cell imaging of ciliary tip ICK, proliferation assays in NIH3T3 and glioblastoma cells\",\n      \"pmids\": [\"23743448\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation of ICK by CDK20 not biochemically mapped here\", \"Mechanism connecting ciliary control to proliferation incompletely defined\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Defined three distinct CDK20 effector arms—Hedgehog/ciliary IFT, KEAP1/NRF2 cytoprotection, and EZH2/NF-κB/IL-6 immunosuppression—broadening its role beyond cilia into oncogenic and redox signaling.\",\n      \"evidence\": \"Mouse mutant genetics with Hh epistasis and ciliary localization (PLoS Genet); TAP/Co-IP with ETGE-motif competition and NRF2 reporters (Oncogene); CRISPR/transgenic mice with ChIP and immunosuppression assays (Gut)\",\n      \"pmids\": [\"28817564\", \"28534518\", \"28939663\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether KEAP1 binding and kinase activity are mechanistically coupled is unresolved\", \"Direct kinase substrates within the NF-κB/EZH2 arm not identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Mapped a STAT3–AR–mTORC1 feedforward circuit downstream of CDK20 driving metabolic-oncogenic signaling and MDSC recruitment.\",\n      \"evidence\": \"Lentiviral ablation and transgenic hepatic induction in mice, ChIP for STAT3–AR co-occupancy, phospho-pathway readouts (GSK3β, mTORC1 substrates)\",\n      \"pmids\": [\"30523261\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct kinase target initiating the loop not pinpointed\", \"Connection between this circuit and the ciliary kinase function unexplored\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Placed CDK20 (DYF-18) genetically upstream of MAK (DYF-5) and upstream of axonemal microtubule stability, mechanistically linking the cascade to tubulin turnover and cilia length/branching.\",\n      \"evidence\": \"C. elegans genetics with tubulin and IFT mutant epistasis, live IFT motor imaging, EBP-2 dynamics\",\n      \"pmids\": [\"30955935\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Biochemical demonstration of DYF-5 activation-loop phosphorylation not shown in this system\", \"Generalization to mammalian axonemes inferred, not directly tested\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showed CDK20 requires both kinase activity and BROMI/TBC1D32 binding to control IFT turnaround at the ciliary tip, situating it upstream of ICK with ICK-like KO phenotypes.\",\n      \"evidence\": \"CCRK-KO cells with WT vs. kinase-dead and BROMI-binding mutant rescue, IFT/membrane receptor immunofluorescence, extracellular vesicle analysis\",\n      \"pmids\": [\"34624068\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether BROMI is a substrate or a scaffold for substrate presentation unclear\", \"Direct phosphorylation event at the tip not biochemically captured\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Defined the multi-protein tip complex (CDK20–BROMI–FAM149B1–CFAP20) acting together upstream of ICK, since KO of each component produced identical ciliary defects.\",\n      \"evidence\": \"Reciprocal Co-IP defining complex composition, KO cells with BROMI-binding mutant rescue, immunofluorescence\",\n      \"pmids\": [\"35609210\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Stoichiometry and order of assembly of the complex not resolved\", \"Catalytic substrate(s) within the complex not identified\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Extended the CDK20–MAK/ICK axis to photoreceptor ciliary maintenance, establishing physiological relevance for retinal survival.\",\n      \"evidence\": \"Mouse Ccrk conditional KO with retinal degeneration phenotyping, epistasis with Mak/Ick, IFT immunofluorescence\",\n      \"pmids\": [\"39293864\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single study\", \"Direct activation-loop phosphorylation of MAK/ICK in photoreceptors not biochemically shown\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Provided direct biochemical proof that CDK20 phosphorylates the CDKL5 activation loop to activate it and control its ciliary transport and flagellar length, completing the mechanistic logic of the cascade; also implicated CDK20 in KU70 stabilization and NHEJ.\",\n      \"evidence\": \"MS phosphorylation mapping and kinase-activation reconstitution in Chlamydomonas with Cdk20-KO rescue in mouse (PLoS Biol); Co-IP, EJ5-GFP NHEJ reporter and AR-luciferase in breast cancer cells (Cells)\",\n      \"pmids\": [\"41385589\", \"40940753\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"KU70 interaction rests on single Co-IP without reciprocal validation\", \"Whether KU70 stabilization requires CDK20 catalytic activity not established\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CDK20 itself is activated and regulated, and how its ciliary kinase function mechanistically integrates with its oncogenic NRF2/NF-κB/STAT3-AR and DNA-repair roles, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No identified activating cyclin/partner or upstream regulator of CDK20 catalytic activity\", \"No structural model linking kinase, ETGE, and BROMI-binding functions\", \"Whether oncogenic circuits depend on ciliary cascade substrates is untested\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [11, 8, 7]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [11, 8]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [3, 12]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [1, 4, 8, 9, 11]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [4]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [4, 2, 5]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [4, 10]},\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [3]},\n      {\"term_id\": \"R-HSA-73894\", \"supporting_discovery_ids\": [12]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [2, 5]}\n    ],\n    \"complexes\": [\"CDK20\\u2013BROMI(TBC1D32)\\u2013FAM149B1\\u2013CFAP20 ciliary tip complex\"],\n    \"partners\": [\"ICK/CILK1\", \"MAK\", \"CDKL5\", \"BROMI/TBC1D32\", \"FAM149B1\", \"KEAP1\", \"KU70\", \"CFAP20\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}