Hsp70 blocks Apo-2L/TRAIL–induced apoptosis. (A) HL-60/Neo and HL-60/hsp70 cells were treated with Apo-2L/TRAIL at the indicated concentrations for 24 hours. Following these treatments, the percentages of apoptotic cells were determined by annexin-V staining followed by flow cytometry. Values represent the mean ± SE of 3 experiments. (B) K562 and K562/hsp70 AS cells were treated with Apo-2L/TRAIL at the indicated concentrations for 24 hours, and the percentages of apoptotic cells were determined by annexin-V staining followed by flow cytometry. (C) Cell lysates of untreated and Apo-2L/TRAIL–treated HL-60/Neo and HL-60/hsp70 cells also were immunoblotted with antibodies to DR4, DR5, caspase-8, FLIPL, and PARP. β-actin levels were used as loading control. (D) HL-60/Neo and HL-60/hsp70 cells were treated with Apo-2L/TRAIL at the indicated concentration for 4 hours. After this, from the cell lysates, immunoprecipitates with anti-DR5 and anti-DR4 antibodies were immunoblotted with anti-hsp70, anti–caspase-8, anti-FADD, or anti-DR5 antibody.
