Smac mimetic and dexamethasone cooperate to induce caspase activation and mitochondrial perturbations. Cells were treated for indicated times (A-C) or for 5 hours (D, Jurkat) or 6 hours (D, Molt-4) with dexamethasone (Jurkat: 300 µM, Molt-4: 200 µM) and/or BV6 (Jurkat: 7 µM, Molt-4: 5 µM). (A) Caspase activation was analyzed by western blotting, active cleavage fragments are indicated by arrowheads, and unspecific bands by asterisk. (B) MMP was assessed by flow cytometry. (C) Cell death was determined by forward/side scatter analysis and flow cytometry. (D) Bak and Bax activation was determined by immunoprecipitation using active conformation-specific antibodies. (B-C) Mean and SD of 3 experiments performed in triplicate are shown; *P < .05; **P < .01 comparing BV6/dexamethasone-treated to control cells.