Mechanism
p16INK4a (CDKN2A)
Reference definition for a cellular-senescence node.
Definition
Category: Arrest effector / biomarker
Also known as: p16, CDKN2A, INK4a
A cyclin-dependent kinase inhibitor that blocks CDK4/6, keeping the retinoblastoma protein active and enforcing cell-cycle arrest. p16INK4a expression rises with age across many tissues and is the canonical marker used to identify and genetically target senescent cells.
Key points
- Genetic clearance of p16INK4a-high cells (INK-ATTAC model) is the causal evidence that senescent-cell burden limits healthy lifespan in mice.
- p16 is a marker and effector, not itself a drug target for current senolytics.
- p16 positivity alone does not define senescence — it is used alongside SA-beta-gal, p21, and SASP markers.
Related interventions
Sourcing
Baker et al. 2011/2016 (INK-ATTAC); standard senescence reviews.
Reference synthesis (tier 4); verification: review_level_2026-07-12.