Seroatlas · Human Serome Atlas

CDKN2A

Cyclin-dependent kinase inhibitor 2A

Also known as: ARF, CDK4I, CDKN2, CDN2A_HUMAN, CMM2, INK4, INK4a, MLM, MTS1, p14, p14ARF, p16, P16-INK4A, p16INK4a, p19, p19Arf

Cross-references: UniProt · Ensembl · Human Protein Atlas · GeneCards · NCBI Gene

Protein identityUniProt · HPA

UniProt accession
P42771
Gene
CDKN2A
Ensembl
ENSG00000147889
Chromosome
9
Canonical length
156 aa
Protein class
Cancer-related genes, Disease related genes, Human disease related genes, Plasma proteins, Predicted intracellular proteins
Subcellular location
Nucleoplasm

OverviewNCBI Gene

This gene generates several transcript variants which differ in their first exons. At least three alternatively spliced variants encoding distinct proteins have been reported, two of which encode structurally related isoforms known to function as inhibitors of CDK4 kinase. The remaining transcript includes an alternate first exon located 20 Kb upstream of the remainder of the gene; this transcript contains an alternate open reading frame (ARF) that specifies a protein which is structurally unrelated to the products of the other variants. This ARF product functions as a stabilizer of the tumor suppressor protein p53 as it can interact with, and sequester, the E3 ubiquitin-protein ligase MDM2, a protein responsible for the degradation of p53. In spite of the structural and functional differences, the CDK inhibitor isoforms and the ARF product encoded by this gene, through the regulatory roles of CDK4 and p53 in cell cycle G1 progression, share a common functionality in cell cycle G1 control. This gene is frequently mutated or deleted in a wide variety of tumors, and is known to be an important tumor suppressor gene. [provided by RefSeq, Sep 2012]

Canonical amino-acid sequenceUniProt

156 residues, UniProt reviewed canonical sequence.

>P42771|CDKN2A
     1  MEPAAGSSME PSADWLATAA ARGRVEEVRA LLEAGALPNA PNSYGRRPIQ VMMMGSARVA
    61  ELLLLHGAEP NCADPATLTR PVHDAAREGF LDTLVVLHRA GARLDVRDAW GRLPVDLAEE
   121  LGHRDVARYL RAAAGGTRGS NHARIDAAEG PSDIPD

LocalizationUniProt · AlphaFold · HPA

Whether an antibody against CDKN2A can act on the native protein depends on physical access: surface and secreted proteins are reachable by circulating antibodies, intracellular proteins usually are not.

Antibody reachability
Intracellular
Secreted
No
Transmembrane segments
0
Mean surface accessibility (rSASA)
0.36
Highest tissue expression
43 nTPM

Expression across tissuesHPA

Tissue

  • choroid plexus: 43 nTPM
  • pituitary gland: 36 nTPM
  • testis: 15 nTPM
  • adrenal gland: 10 nTPM
  • esophagus: 7.5 nTPM
  • blood vessel: 5.7 nTPM

Single-cell type

  • late spermatids: 681 nCPM
  • gastric progenitor cells: 511 nCPM
  • early spermatids: 202 nCPM
  • late primary spermatocytes: 158 nCPM
  • endometrial ciliated cells: 94 nCPM
  • somatotrophs: 87 nCPM

Immune cell

  • T-reg: 38 nTPM
  • memory CD8 T-cell: 18 nTPM
  • naive B-cell: 16 nTPM
  • MAIT T-cell: 14 nTPM
  • memory CD4 T-cell: 12 nTPM
  • memory B-cell: 11 nTPM

Brain region

  • choroid plexus: 57 nTPM
  • white matter: 11 nTPM
  • cerebral cortex: 9.7 nTPM
  • basal ganglia: 8.8 nTPM
  • thalamus: 8.1 nTPM
  • medulla oblongata: 7 nTPM

DiseaseUniProt · ClinVar · IEDB · PubMed

Four sources answering four different questions about CDKN2A.

Disease | AllUniProt

Conditions CDKN2A is implicated in, by any mechanism.

  • Melanoma, cutaneous malignant 2 (CMM2) MIM:155601
  • Familial atypical multiple mole melanoma-pancreatic carcinoma syndrome (FAMMMPC) MIM:606719
  • Melanoma-astrocytoma syndrome (MASTS) MIM:155755

Disease | GeneticClinVar

173 pathogenic / likely-pathogenic of 1,595 ClinVar records.

Conditions with pathogenic or likely-pathogenic variants.

Genetic constraint and essentialitygnomAD · DepMap

Does the body need this protein intact? Low LOEUF or a strong DepMap dependency means loss or blockade of the protein is likely to be felt.

gnomAD LOEUF (loss-of-function intolerance)
0.95
gnomAD pLI
0.39
gnomAD missense Z
-1.01
DepMap mean gene effect
0.16
DepMap dependency class
none

Cancer expressionTCGA

Across TCGA tumor cohorts, this protein is over-expressed in roughly 5% of surveyed tumor types (aggregate summary; per-cohort expression, alteration, and survival load in the interactive view).

OntologyGO

Biological processes

Molecular functions

Cellular components

Protein domainsUniProt · Pfam · InterPro

KeywordsUniProt

InteractionsUniProt · HPA

Protein binding partners of CDKN2A in the human serome: UniProt-annotated complex subunits plus reported interactors. Each links to its own Seroatlas record.

Antibody and autoantibody relevanceSeroatlas analysis

Seroatlas reads CDKN2A as an antibody target. Whether an autoantibody or antibody against CDKN2A could matter depends on whether native CDKN2A is physically reachable, whether the body needs it intact, and whether it acts in a disease-relevant tissue.

CDKN2A is annotated as predominantly intracellular. Intracellular proteins are common autoantibody markers, becoming visible to the immune system after cell injury or altered processing, but are usually markers of disease rather than direct drivers.

Annotation status

The present source text does not explicitly label CDKN2A as an autoantigen. Seroatlas presents hypothesis context only and does not manufacture a known-serology claim.

Canonical record: https://seroatlas.com/gene/CDKN2A. Study-independent annotations aggregated from UniProt, Human Protein Atlas, PubMed, IEDB, Pfam, InterPro, Gene Ontology, AlphaFold, gnomAD, DepMap, ClinVar, TCGA. Catalog release seroatlas-reviewed-human-uniprot-20260313.

Seroatlas is the reference for exploring autoantibody and antibody serology at the human-protein level: the autoreactome and human serome, multiplex serology (HuProt, HuScan, VirScan, PhIP-Seq).

© 2026 · Seroatlas, Discover Oregon LLC · Terms of use

Loading the interactive Seroatlas protein explorer...