fig6

Figure 6. The intrinsic apoptotic pathway was involved in the TRAIL-induced apoptosis in the A549BTZR cells, though reduced levels of Bcl-xL were not a determinant. (A) The silencing of Bcl-xL, as shown by western blot analysis, resulted in enhanced cell death in the A549 and SW1573 cells after 24 h exposure to 100 ng/mL TRAIL; (B) A549BTZR cells were transfected with a control puromycin vector or a Bcl-xL-containing vector, as shown by western blot analysis; (C) Cell death was measured in the A549BTZR cells and the transfected variants after incubation with 100 ng/mL TRAIL for 24 h; (D) Western blot analysis was used to detect the cleavage of caspase-8, -9, -3, and PARP after exposure to 100 ng/mL TRAIL for several time intervals in the A549BTZR and A549BTZR-Bcl-xL cells; (E) Cell death was determined in the H460 and H460-Bcl-xL cells after exposure to 10 ng/mL TRAIL for 24 h; (F) Cell death was measured in A549BTZR and A549BTZR-Bcl-xL cells after silencing of BID. ^***P < 0.001; ^**P < 0.01; ^*P < 0.05. TRAIL: TNF-related apoptosis-inducing ligand; TNF: tumor necrosis factor; Bcl-xL: B-cell lymphoma-extra large; BID: BH3 Interacting Domain Death Agonist.