γ-Irradiation induces identical cell cycle responses in normal and uncorrected FA(C) cell lines. Cells were treated with 500 rads of γ-irradiation. Following irradiation the cells were washed extensively and placed in culture in a 12-well plate. Twenty-four hours after irradiation the cells were harvested along with nonirradiated control cells. DNA content was measured by PI staining and flow cytometry. Results of a representative experiment are shown. The shaded area represents cells in S phase.