Effects of MEK1/2 inhibitor U0126 on MAPK, phospho-MAPK (Thr202/Tyr204), and cleavage of caspase 3, caspase 7 and PARP in pUSE-9 and H-MEK1-15 clones. pUSE-9 and H-MEK1-15 cells were cultured as described under Experimental Procedures. Cells were incubated with PSF medium containing 0.1% DMSO or indicated concentrations of U0126 for 24 h. Total cell lysate was prepared for Western blot analysis as described under Experimental Procedures. Blots containing total cell lysate were incubated with mouse anti-α-tubulin (A), mouse anti-MAPK (B), mouse anti-phospho-MAPK (Thr202/Tyr204) (C), rabbit anti-caspase 3 (D), rabbit anti-cleaved caspase 7 (E), rabbit anti-cleaved PARP (F) antibodies. All the antibodies were used at a final concentration of 1 μg per ml. Representative blots are shown.