Senescence-associated beta-galactosidase (SA-β-gal or SABG) is a hypothetical hydrolase enzyme that catalyzes the hydrolysis of β-galactosides into monosaccharides only in senescent cells.Its existence was proposed in 1995 by Dimri et al. following the observation that when beta-galactosidase assays were carried out at pH 6.0 only cells in senescence state develop staining.