FIG. 2.

p53 prolongs G₂ cell cycle arrest after exposure to IR or ADR. Cells were harvested at the indicated times and analyzed by flow cytometric analysis. (A) Cells were treated with IR (8, 12, 20, and 30 Gy) and incubated for 15 h, after which time cells were cultured for an additional 24, 48, or 72 h in the presence or absence of PonA. (B) Cells were treated with ADR (90, 175, 350, or 525 nM) for 17 h, the drug was washed out, and the cells were cultured for an additional 24, 48, or 72 h in the presence or absence of PonA. Fifteen thousand events were analyzed for each condition, and all histograms were plotted by using the same scale for both axes. Results are representative of two independent experiments.