Effect of z-VAD on the LY294002-induced apoptosis. (A) Effect of z-VAD/fmk on LY294002-induced apoptosis in DLBCL cells. SUDHL-4, SUDHL-5, and SUDHL10 cells were pretreated with 80 μM z-VAD/fmk for 2 hours and subsequently treated with 10 and 25 μM LY294002 for 24 hours. Apoptosis was measured by annexin V/PI staining. (B) Effect of z-VAD/fmk on LY294002-induced cell death in DLBCL cells. SUDHL-4, SUDHL-5, and SUDHL-10 cells were pretreated with 80 μM z-VAD/fmk for 2 hours and subsequently treated with 10 and 25 μM LY294002 for 24 hours. Live and dead cells were scored using trypan blue exclusion dye. The graph displays the mean ± SD of 3 independent experiments. (C) z-VAD/fmk abrogates LY294002-induced activation of caspase-3. SUDHL-4, SUDHL-5, and SUDHL10 cells were pretreated with 80 μM z-VAD/fmk for 2 hours and subsequently treated with 25 μM for 24 hours. Cells were lysed and equal amounts of proteins were separated by SDS-PAGE, transferred to PVDF membrane, and immunoblotted with antibodies against procaspase-3, cleaved caspase, and actin as indicated.