Homo sapiens Gene: CDKN1A
InnateDB Gene IDBG-85033.6
Last Modified 2014-10-13 [Report errors or provide feedback]
Gene Symbol CDKN1A
Gene Name cyclin-dependent kinase inhibitor 1A (p21, Cip1)
Synonyms CAP20; CDKN1; CIP1; MDA-6; P21; p21CIP1; SDI1; WAF1
Species Homo sapiens
Ensembl Gene ENSG00000124762
Encoded Proteins
cyclin-dependent kinase inhibitor 1A (p21, Cip1)
cyclin-dependent kinase inhibitor 1A (p21, Cip1)
cyclin-dependent kinase inhibitor 1A (p21, Cip1)
cyclin-dependent kinase inhibitor 1A (p21, Cip1)
cyclin-dependent kinase inhibitor 1A (p21, Cip1)
Protein Structure
Useful resources Stemformatics EHFPI ImmGen
InnateDB Annotation from Orthologs
[Mus musculus] During sepsis-induced generation of myeloid-derived suppressor cells, transcription factor Nfia represses Cdkn1a to arrest differentiation of Gr1+ CD11b+ cells.
Entrez Gene
Summary This gene encodes a potent cyclin-dependent kinase inhibitor. The encoded protein binds to and inhibits the activity of cyclin-CDK2 or -CDK4 complexes, and thus functions as a regulator of cell cycle progression at G1. The expression of this gene is tightly controlled by the tumor suppressor protein p53, through which this protein mediates the p53-dependent cell cycle G1 phase arrest in response to a variety of stress stimuli. This protein can interact with proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory factor, and plays a regulatory role in S phase DNA replication and DNA damage repair. This protein was reported to be specifically cleaved by CASP3-like caspases, which thus leads to a dramatic activation of CDK2, and may be instrumental in the execution of apoptosis following caspase activation. Multiple alternatively spliced variants have been found for this gene. [provided by RefSeq, Nov 2010]
Gene Information
Type Protein coding
Genomic Location Chromosome 6:36676460-36687339
Strand Forward strand
Band p21.2
ENST00000244741 ENSP00000244741
ENST00000373711 ENSP00000362815
ENST00000405375 ENSP00000384849
ENST00000448526 ENSP00000409259
ENST00000615513 ENSP00000482768
Number of Interactions This gene and/or its encoded proteins are associated with 469 experimentally validated interaction(s) in this database.
They are also associated with 21 interaction(s) predicted by orthology.
Experimentally validated
Total 473 [view]
Protein-Protein 403 [view]
Protein-DNA 64 [view]
Protein-RNA 3 [view]
DNA-DNA 3 [view]
Predicted by orthology
Total 21 [view]
Gene Ontology

Molecular Function
Accession GO Term
GO:0004861 cyclin-dependent protein serine/threonine kinase inhibitor activity
GO:0005515 protein binding
GO:0019912 cyclin-dependent protein kinase activating kinase activity
GO:0030332 cyclin binding
GO:0032403 protein complex binding
GO:0046872 metal ion binding
Biological Process
GO:0000079 regulation of cyclin-dependent protein serine/threonine kinase activity
GO:0000082 G1/S transition of mitotic cell cycle
GO:0000086 G2/M transition of mitotic cell cycle
GO:0000278 mitotic cell cycle
GO:0006468 protein phosphorylation
GO:0006974 cellular response to DNA damage stimulus
GO:0006977 DNA damage response, signal transduction by p53 class mediator resulting in cell cycle arrest
GO:0007050 cell cycle arrest
GO:0007173 epidermal growth factor receptor signaling pathway
GO:0007265 Ras protein signal transduction
GO:0007346 regulation of mitotic cell cycle
GO:0008285 negative regulation of cell proliferation
GO:0008543 fibroblast growth factor receptor signaling pathway
GO:0009411 response to UV
GO:0009636 response to toxic substance
GO:0010033 response to organic substance
GO:0010165 response to X-ray
GO:0010243 response to organonitrogen compound
GO:0010629 negative regulation of gene expression
GO:0014070 response to organic cyclic compound
GO:0030308 negative regulation of cell growth
GO:0030890 positive regulation of B cell proliferation
GO:0031100 organ regeneration
GO:0031668 cellular response to extracellular stimulus
GO:0033158 regulation of protein import into nucleus, translocation
GO:0034605 cellular response to heat
GO:0038095 Fc-epsilon receptor signaling pathway
GO:0042326 negative regulation of phosphorylation
GO:0042493 response to drug
GO:0042771 intrinsic apoptotic signaling pathway in response to DNA damage by p53 class mediator
GO:0043066 negative regulation of apoptotic process
GO:0043068 positive regulation of programmed cell death
GO:0045087 innate immune response
GO:0045736 negative regulation of cyclin-dependent protein serine/threonine kinase activity
GO:0045860 positive regulation of protein kinase activity
GO:0046685 response to arsenic-containing substance
GO:0048011 neurotrophin TRK receptor signaling pathway
GO:0048015 phosphatidylinositol-mediated signaling
GO:0048146 positive regulation of fibroblast proliferation
GO:0051384 response to glucocorticoid
GO:0051412 response to corticosterone
GO:0051726 regulation of cell cycle
GO:0055093 response to hyperoxia
GO:0060574 intestinal epithelial cell maturation
GO:0071479 cellular response to ionizing radiation
GO:0071850 mitotic cell cycle arrest
GO:0071901 negative regulation of protein serine/threonine kinase activity
GO:0090398 cellular senescence
GO:0090400 stress-induced premature senescence
GO:0097193 intrinsic apoptotic signaling pathway
GO:2000278 regulation of DNA biosynthetic process
GO:2000379 positive regulation of reactive oxygen species metabolic process
Cellular Component
GO:0000307 cyclin-dependent protein kinase holoenzyme complex
GO:0005634 nucleus
GO:0005654 nucleoplasm
GO:0005737 cytoplasm
GO:0005829 cytosol
GO:0043231 intracellular membrane-bounded organelle
GO:0048471 perinuclear region of cytoplasm
GO:0070557 PCNA-p21 complex
Mus musculus
Bos taurus
Gene ID
Gene Order
Not yet available
TGF_beta_Receptor pathway
Transcriptional activation of cell cycle inhibitor p21 pathway
p53-Dependent G1 DNA Damage Response pathway
Orc1 removal from chromatin pathway
Removal of licensing factors from origins pathway
Switching of origins to a post-replicative state pathway
SCF(Skp2)-mediated degradation of p27/p21 pathway
Cyclin A:Cdk2-associated events at S phase entry pathway
Cyclin E associated events during G1/S transition pathway
Cyclin D associated events in G1 pathway
AKT phosphorylates targets in the cytosol pathway
PIP3 activates AKT signaling pathway
DAP12 signaling pathway
DAP12 interactions pathway
PI3K/AKT activation pathway
GAB1 signalosome pathway
Signaling by EGFR pathway
PI3K events in ERBB4 signaling pathway
Signaling by ERBB4 pathway
PI3K events in ERBB2 signaling pathway
Signaling by ERBB2 pathway
PI-3K cascade pathway
Signaling by FGFR pathway
Signaling by SCF-KIT pathway
Downstream signal transduction pathway
Signaling by PDGF pathway
Constitutive PI3K/AKT Signaling in Cancer pathway
DNA Replication pathway
Signaling by FGFR in disease pathway
p53-Dependent G1/S DNA damage checkpoint pathway
G1 Phase pathway
Cellular responses to stress pathway
Signalling by NGF pathway
Signaling by EGFR in Cancer pathway
Downstream signaling of activated FGFR pathway
Synthesis of DNA pathway
Mitotic G1-G1/S phases pathway
Role of LAT2/NTAL/LAB on calcium mobilization pathway
S Phase pathway
Innate Immune System pathway
Fc epsilon receptor (FCERI) signaling pathway
G1/S Transition pathway
Signal Transduction pathway
Cell Cycle pathway
DNA Damage/Telomere Stress Induced Senescence pathway
Adaptive Immune System pathway
Transcriptional activation of p53 responsive genes pathway
Immune System pathway
Cellular Senescence pathway
NGF signalling via TRKA from the plasma membrane pathway
Cell Cycle, Mitotic pathway
PI3K/AKT Signaling in Cancer pathway
Senescence-Associated Secretory Phenotype (SASP) pathway
G1/S DNA Damage Checkpoints pathway
Regulation of DNA replication pathway
Signaling by the B Cell Receptor (BCR) pathway
Downstream signaling events of B Cell Receptor (BCR) pathway
Disease pathway
Cell Cycle Checkpoints pathway
ErbB signaling pathway pathway
Cell cycle pathway
Melanoma pathway
Bladder cancer pathway
Glioma pathway
Prostate cancer pathway
Chronic myeloid leukemia pathway
p53 signaling pathway pathway
Pathways in cancer pathway
Hepatitis C pathway
Hedgehog signaling pathway pathway
Class I PI3K signaling events mediated by Akt
Regulation of retinoblastoma protein
Direct p53 effectors
Validated targets of C-MYC transcriptional repression
Glucocorticoid receptor regulatory network
p73 transcription factor network
Angiopoietin receptor Tie2-mediated signaling
C-MYB transcription factor network
E2F transcription factor network
Signaling events mediated by PRL
Regulation of nuclear SMAD2/3 signaling
Signaling events mediated by HDAC Class III
Validated transcriptional targets of TAp63 isoforms
Notch signaling pathway
UniProt Splice Variant
Entrez Gene
UniGene Hs.370771
RefSeq NM_000389 NM_001220777 NM_001220778 NM_001291549 NM_078467
HPRD 00298
RNA Seq Atlas