FTY720 induces cell death in a caspase-dependent manner. (A) Caspase activation and PARP cleavage following treatment with FTY720. Lysates from CC cells treated with 0, 5 and 10 μmol/L FTY720 for 24 h were probed for cleaved-caspase-3, cleaved-caspase-8, cleaved-caspase-9 and cleaved-PARP by western blotting. (B) Caspase inhibition protects against FTY720-induced cell death. CC cells were incubated in 0.1% DMSO, 5 μmol/L FTY720 or a combination of Q-VD-OPH (20 μmol/L) and 5 μmol/L FTY720, followed by annexin V-PI staining 24 h later. Data are presented as the mean ± SD from three independent experiments. (C) Lysates from treated cells were probed for cleaved-caspase-3 or cleaved-PARP by western blotting. The western blot is representative of three independent experiments. β-Actin was used as the internal control.