Figure 4.

The MEK inhibitor PD184352 partly sensitizes EIA + raf but not EIA + Py cells toward apoptosis. (A) PC EIA + Py cells were mock-pretreated or pretreated with 10 and 20 µM PD184352 for 30 minutes, whereas PC EIA + raf cells were mock-pretreated or pretreated with 5 and 10 µM of PD184352 for 30 minutes. Cells were then serum-starved (with 0.2% BSA) for 3 days in the presence of PD184352. (B) PC EIA + Py cells were mock-pretreated or pretreated with 10 and 20 µM of PD184352 for 30 minutes, whereas PC EIA + raf cells were mock-pretreated or pretreated with 2.5 and 5 µM of PD184352 for 30 minutes. Cells were then exposed to 400 µM H₂O₂ for 48 hours in the presence of PD184352. After the treatments described in (A) and (B), cells were subjected to MTT assay, as outlined in Materials and Methods. The results shown are mean ± SD from eight replicate wells per microtiter plate of four different experiments. **P < .01, compared with serum-deprived or H₂O₂-treated cells in the absence of PD184352.