Cell cycle dependence of Mcm4 recovery. Mcm4 FRAP recoveries vary significantly throughout the cell cycle. The IF, calculated from the FRAP intensity 30–60 s after bleaching, is minimal after mitosis, but gradually increases to >60% as G1 phase progresses. Once S phase begins, the IF begins to drop, returning to 0% by G2 phase. Inset graphs show the time (x axis) in log scale. n, number of cells analyzed to calculate the IF and standard deviation of the mean. The gray bars indicate the initial appearance of PCNA foci.