OSU03012 induces activation of intrinsic pathway of apoptosis, as shown by activation of caspase-9 but not caspase-8. (A) OSU03012 induces activation of the intrinsic pathway of apoptosis. Protein lysates from cells treated for 4 and 24 hours with 10 μM OSU03012 were probed for caspase-8 by immunoblot (M indicates media; 12, 10μM OSU0312). Positive control is lysate from irradiated Jurkat cells. Data are representative of 8 patients. (B) Protein lysates from cells treated for 4 and 24 hours with 10 μM OSU03012 were probed for caspase-9 by immunoblot (M indicates media; 12, 10 μM OSU0312). Positive control is lysate from irradiated Jurkat cells. Data are representative of 8 patients.