ELL-12 induces caspase-8 activation and apoptosis independently of the CD95 receptor/ligand system in H9 lymphoma cells. Extracts from H9 cells treated with 10 and 50 μg/mL ELL-12 or 50 ng/mL anti-Fas antibody for 16 hours were resolved by SDS-PAGE and probed with anti–caspase-8 antibody (A) or anti-CD95L antibody (B). Migrations indicated are full-length caspase-8, the cleavage intermediates p43 and p41, the active subunits p18 and p16, and full-length CD95L. H9 cells were pretreated with 300 ng/mL antagonist anti-Fas MoAb (clone ZB4) for 1 hour and then treated with 50 ng/mL anti-Fas MoAb or 10 and 50 μg/mL ELL-12 for an additional 16 hours (C). Apoptosis was assessed by Hoechst staining. Results are the means ± SD of 3 independent experiments.