CDKN1B (Cyclin Dependent Kinase Inhibitor 1B)
A key regulator of cell cycle progression and tumor suppressor gene encoding p27/Kip1 protein.
Gene Information Card
| Symbol | CDKN1B |
|---|---|
| Full Name | Cyclin Dependent Kinase Inhibitor 1B |
| Gene Type | Protein coding |
| Chromosomal Location | 12p13.1 |
| NCBI Gene ID | 1027 ncbi.nlm.nih.gov/gene/1027 |
| Ensembl ID | ENSG00000111276 |
| UniProt ID | P46527 |
| OMIM ID | 600778 |
| HGNC ID | 1785 |
| Aliases | p27, Kip1, MEN4, CDKN4 |
Description
CDKN1B encodes p27/Kip1, a cyclin-dependent kinase inhibitor that binds to and inhibits cyclin E/CDK2 and cyclin D/CDK4 complexes, thereby regulating G1/S cell cycle progression. It functions as a tumor suppressor and is frequently inactivated in various human cancers. Germline mutations cause multiple endocrine neoplasia type 4 (MEN4).
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Multiple Endocrine Neoplasia Type 4 (MEN4) | Germline loss-of-function mutations in CDKN1B lead to reduced p27 activity, promoting endocrine tumorigenesis. | OMIM #610755; ClinVar |
| Breast Cancer | Reduced p27 expression or cytoplasmic mislocalization correlates with poor prognosis. | COSMIC; NCBI |
| Prostate Cancer | Loss of p27 expression is associated with aggressive disease and progression. | COSMIC; PubMed |
| Colorectal Cancer | Somatic mutations and decreased p27 levels contribute to uncontrolled proliferation. | COSMIC; ClinVar |
| Lung Cancer | Epigenetic silencing or mutation of CDKN1B promotes cell cycle dysregulation. | COSMIC |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Adipose tissue | 8.2 | Medium |
| Brain | 6.5 | Medium |
| Breast | 7.1 | Medium |
| Colon | 9.3 | Medium |
| Kidney | 10.5 | Medium |
| Liver | 7.8 | Medium |
| Lung | 8.9 | Medium |
| Prostate | 9.0 | Medium |
| Skin | 6.8 | Medium |
| Testis | 11.2 | High |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 12.5 | Cervical cancer cell line |
| MCF7 | 10.3 | Breast cancer cell line |
| A549 | 9.8 | Lung cancer cell line |
| HEK293 | 11.0 | Embryonic kidney cell line |
| HCT116 | 10.7 | Colorectal cancer cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.59C>T (p.Pro20Leu) | Missense | <0.1% | Reduced protein stability; associated with MEN4 |
| c.227G>A (p.Trp76*) | Nonsense | <0.1% | Premature truncation; loss of function |
| c.326T>C (p.Ile109Thr) | Missense | <0.1% | Impaired CDK binding; loss of function |
| c.1A>G (p.Met1Val) | Start loss | <0.1% | Translation initiation defect; loss of function |
| c.68_69del (p.Glu23fs) | Frameshift | <0.1% | Frameshift leading to premature stop; loss of function |
Mutation functional classification
Loss of Function (LOF)
Most CDKN1B mutations are loss-of-function, reducing p27 protein levels or impairing CDK inhibition, leading to unchecked cell proliferation.
Gain of Function (GOF)
No confirmed gain-of-function mutations reported in CDKN1B.
Dominant Negative (DN)
Some missense mutations (e.g., p.Ile109Thr) may exert dominant-negative effects by forming inactive complexes with wild-type p27.
View complete mutation data：
Gene Ontology (GO)
| • GO:0004861 - cyclin-dependent protein serine/threonine kinase inhibitor activity | • GO:0005515 - protein binding |
| • GO:0005737 - cytoplasm | • GO:0005634 - nucleus |
| • GO:0007049 - cell cycle | • GO:0051726 - regulation of cell cycle |
| • GO:0008285 - negative regulation of cell population proliferation | • GO:0043066 - negative regulation of apoptotic process |
Pathways
• Cell Cycle
• G1/S Transition (Reactome: R-HSA-69278)
• p53-Independent G1/S DNA Damage Checkpoint (Reactome: R-HSA-69620)
• CDK-mediated phosphorylation and removal of Cdc6 (Reactome: R-HSA-69017)
Protein Summary
p27/Kip1 is a 198-amino acid protein (22 kDa) that contains a conserved N-terminal cyclin-dependent kinase (CDK) inhibitory domain. It binds to cyclin-CDK complexes, blocking kinase activity and arresting cells in G1 phase. p27 stability is regulated by phosphorylation (e.g., at Thr187 by CDK2) leading to ubiquitin-mediated degradation. Nuclear localization is critical for its tumor suppressor function; cytoplasmic mislocalization is oncogenic.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CDKN1B Knockout HEK293 Cell Line | EDJ-KQ766 | Human | 1027 | Details Get a Quote |
| CDKN1B Knockout A-549 Cell Line | EDC08330 | Human | 1027 | Details Get a Quote |
| CDKN1B Knockout HCT 116 Cell Line | EDJ-KQ19461 | Human | 1027 | Details Get a Quote |
| CDKN1B Knockout HeLa Cell Line | EDJ-KQ19462 | Human | 1027 | Details Get a Quote |
| Cdkn1b Knockout RAW 264.7 Cell Line | EDJ-KZ144 | Mouse | 12576 | Details Get a Quote |
| CDKN1B(p.G97*)Point Mutation in 22Rv1 Cell Line | EDC90367 | Human | 1027 | Details Get a Quote |
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