FIGURE 5.

MNNG-induced apoptosis occurs in a mismatch repair-dependent manner in the first S phase after damage. Representative cell cycle profiles of control, MSH2 knockdown (KD), or MLH1 knockdown YK26 cells originally synchronized in mitosis by nocodazole were measured by flow cytometry. Cells were released into normal growth medium and then, with or without a 4 h treatment with 2 μm MNNG, harvested at different time points after release. The arrows indicate sub-G₁ populations of cells. The absence of sub-G₁ populations observed in MSH2 knockdown cells indicates a loss of the apoptotic response observed in control cells.