Characterization of senescence phenotypes in AT13387-treated C666-1. (A) Staining of senescence-associated β-galactosidase (SA-β-gal). Senescent cells were identified as cells stained blue after 72 hrs of AT13387 treatment. Scale bar = 50 μm. (B) DAPI staining and quantification of senescence-associated heterochromatic foci (SAHF). Upper panel: microscopic image showing formation of SAHF in C666-1 cells with AT13387 treatment for 96 hrs. Scale bar = 10 μm, red arrow indicated cells with typical SAHF. Lower panel: bar chart showing the percentage of cells with SAHF. At least 200 cells were counted from different microscopic fields for each treatment. Results were expressed as the mean ± S.D. of three independent experiments; *p < 0.05.