c-MYC expression modulates caspase-9 activation after IR, cispatin, and etoposide treatment of DAOY MB cells. IR (A) triggers caspase-9 cleavage exclusively in c-MYC over-expressing DAOY cells. Caspase-9 cleavage is more pronounced in DAOY M2 cells following treatment with cisplatin (B), or etoposide (C). Cells were irradiated with 5 Gy, treated with cisplatin (0.15 μg/ml) or with etoposide (0.19 μg/ml). Lysates were analyzed at the indicated time points by Western blotting for caspase 8 and 9, and β-actin. Representative blots (two independent experiments) are shown.