Figure 6. FTY720 and TRAIL-mediated apoptosis is independent of ROS signaling in Caki cells.

(A) Caki cells were treated with 15 μM FTY720 for the indicated time periods and loaded with H₂DCF-DA fluorescent dye. The H₂DCF-DA fluorescence intensity was detected by flow cytometry. (B) Caki cells were pretreated with 200 μM trolox (Trol), 5 mM NAC, and 2 mM GEE for 30 min and then stimulated with 15 μM FTY720 for 24 h. The protein expression levels of DR5, Mcl-1 and actin were determined by western blotting. The level of actin was used as a loading control. (C) Caki cells were pretreated with 200 μM trolox (Trol), 5 mM NAC, and 2 mM GEE for 30 min, and then stimulated with 15 μM FTY720 plus 50 ng/ml TRAIL for 24 h. Apoptosis was analyzed in the sub-G1 population by FACS analysis. The protein expression levels of PARP and actin were determined by western blotting. The level of actin was used as the loading control. The values in (C) represent the mean ± SD from three independent samples.