CDKN2A and renal fibrosis: Moreover, the detection of SA-β-galactosidase (SA-β-Gal) showed that the activity of SA-β-Gal in the cytoplasm of renal tubular epithelial cells increased, and the cell cycle inhibition of the expression of senescence-related gene cell cycle inhibitor p16INK4A protein and p21 protein increased, indicating that renal fibrosis in db/db mice was accompanied by cell senescence.