Figure 5.

Inhibition of the MAPK pathway increases the proportion of cells in G₂/M after irradiation. A431-TR25-EGFR-AS cells were pretreated for 30 min before irradiation with MEK1/2 inhibitors (PD98059, 10 μM; U0126, 2 μM), EGFR inhibitor AG1478 (100 nM), or DMSO control. Cells were irradiated (2 Gy), and the cell cycle profiles under each condition were determined 6, 24, and 48 h after irradiation by flow cytometry. Apoptosis determination at 24 h was by TUNEL staining. (A) Cell cycle profiles of A431-TR25-EGFR-AS cells 6 h after irradiation. (B) Cell cycle profiles of A431-TR25-EGFR-AS cells 24 h after irradiation. (C) Cell cycle profiles of A431-TR25-EGFR-AS cells 48 h after irradiation. (D) Determination of apoptosis by TUNEL assay in A431-TR25-EGFR-AS cells 24 and 48 h after irradiation. Data are the means of five separate experiments (±SEM); *p < 0.01 greater than control value; ^#p < 0.05 less than corresponding value at 24 h.