Figure 4

Protection of HCT116 cells against TRAIL by STI571 is associated with JNK and p38 signaling. HCT116 (A, D), LNCaP (B), and PC3 cells (C) were treated with TRAIL (50 ng/ml), STI571 (0.3 μM) and/or anisomycin (10 μM) for the time indicated. Then protein levels of JNK, p38, and ERK were determined (left panel). Traces were representative of three separate experiments with similar results. In some experiments, cells were pretreated with SB203580 (10 μM), SP600125 (20 μM), STI571 (0.3 μM) and/or zVAD (20 μM) as indicated for 30 min, and then TRAIL (50 ng/ml) or anisomycin (10 μM) was added. After 24 h incubation, cell viability was determined by the MTT assay (right panel). * p < 0.05, indicating a significant reduction in cell apoptosis by STI571. ^# p < 0.05, indicating a significant reduction in TRAIL-elicited apoptosis by kinase inhibitors.