Figure 2. Cells cultured in BCAA_3 medium have higher activities to induce premature senescence.

(A) HepG2 cells cultured in BCAA_1, 3, 5 and BCAA_5 with 100 nM rapamycin were treated with 10 µM etoposide for 2 days, and observed with microscope after SA-β-Gal staining assay. (B, C) HepG2 cells cultured in BCAA medium with or without 100 nM rapamycin as indicated were treated with 10 µM etoposide (B) or 2 µM bleomycin (C) for 2 days. (D) U2OS cells cultured in RPMI-based medium with or without 100 nM rapamycin as indicated were treated with 2 µM etoposide for 7 days. For the assay of SA-β-Gal activity, cells stained with blue color were counted as described in Materials and Methods. The data (mean ± S.D.) were obtained from at least three independent experiments. Significant test results (P values) are shown.