Senescence-associated beta-galactosidase (SA-beta-gal)

Definition

Category: Biomarker (assay)

Also known as: SA-beta-gal, senescence stain

A histochemical stain detecting lysosomal beta-galactosidase activity at pH 6, elevated in many senescent cells. It is the classic, widely used marker of senescence but is not perfectly specific, so it is interpreted alongside p16, p21, and SASP markers rather than alone.

Key points

• SA-beta-gal is a convenient readout in tissue biopsies used to gauge senescent-cell burden in human pilots.
• It is a biomarker, not a drug target.
• Because specificity is imperfect, no single marker defines senescence.

Sourcing

Dimri et al. 1995 (original assay); standard reviews.

Reference synthesis (tier 4); verification: review_level_2026-07-12.