Figure 2. Cell-cycle progression in response to MMS and ionizing radiation. FACS analysis was performed on cells collected at each timepoint indicated. FACS profiles for wild-type cells (left panel) and mec1 cells (right panel) are shown following MMS treatment (A) and ionizing radiation (B). The FACS profile of the asynchronous cells used as the reference sample in the ionizing radiation timecourse is shown in gray. Arrows indicate peaks in the profiles that represent cells with 1N or 2N DNA content, corresponding to cells in G1 phase or G2/M phase, respectively.