ALP-induced apoptosis is independent of Fas/CD95-FasL/CD95L interaction, and ALP treatment enhances cytotoxicity of death receptor ligands. (A) Fas/CD95-FasL/CD95L interaction is not required for ALP-induced apoptosis. MM144 cells were untreated or preincubated with blocking SM1/23 antibody before addition of 50 ng/mL cytotoxic anti-Fas/CD95 CH-11 monoclonal antibody, 10 μM edelfosine, or 10 μM perifosine. After 24 hours of incubation, apoptosis was quantitated by flow cytometry. (B) ALPs enhance cytotoxicity of Fas/CD95 and TRAIL ligands. MM144 cells were untreated or treated for 12 hours with 10 μM edelfosine (EDLF) or perifosine (PERF), followed by addition of 50 ng/mL cytotoxic anti-Fas/CD95 CH-11 monoclonal antibody, 100 ng/mL FasL/CD95L, or 50 ng/mL TRAIL for 12 hours. Untreated control cells and samples treated with 10 μM edelfosine or perifosine for 12 hours and 24 hours were also run in parallel. Apoptosis was then determined by flow cytometry. Data shown are means ± SD of 3 independent experiments.