BH3 profiling reveals a mitochondrial basis for acquired resistance to ABT-737. (A) Mitochondria were isolated from OCI-Ly1 and OCI-Ly1 R10 cells and treated with different concentrations of peptides. Cytochrome c release was measured by ELISA. Shown is the average and SE of 3 independent experiments. (B) Mitochondria were isolated from SU-DHL-4 and SU-DHL-4 R2 cells and treated with different peptides. Cytochrome c release was measured by ELISA. Shown is the average and SE of 3 independent experiments. In both cases, ABT-737 was removed from culture medium for at least 1 week.