ASMase inhibitor desipramine blocks α-TEA-induced apoptosis. MDA-MB-231 cells were pre-treated with 12.5 μM desipramine for 2 hrs followed by treating the cells with 40 μM α-TEA for different time periods. A, Western blot analyses of cellular lysates were performed to detect cleavage of caspases-8 &-9 and PARP. B, ASMase activity was detected using the Acid Sphingomyelinase Assay kit (Echelon). C, Ceramide levels in cell surface membranes were detected by FACS analyses after reaction of living cells with primary ceramide antibody and fluorescence labeled secondary antibody after 4 hours of α-TEA treatment. Data are representative of three independent experiments. Data in B are presented as means ± S.D. of three independent experiments. (* = Significantly different, P < 0.05).