Effect of PAS on Bax conformational change, cytochrome c release, and Bax insertion into the mitochondria. CLL cells were incubated for 18 hours with no addition (NA) or 5 or 20 μM PAS in the presence of the pan-caspase inhibitor ZVAD. (A) Cell extracts were immunoprecipitated using an antibody specific for the proapoptotic conformation of Bax (Bax*). Precipitates were analyzed by Western blotting. IgL, antibody light chain, NSB, nonspecific band. (B) DDF was performed to determine the movement of cytochrome c and Bax within the cell after PAS treatment. Fractions (Fn) 1, 2, and 3 correspond to cytosolic, mitochondrial plus organellar, and nuclear fractions, respectively. Data shown are for patient AS9 and are typical of 5 experiments.