Figure 5. G2/M cells with DNA lesions have increased p21 and reduced Rb phosphorylation.

A & B. Histograms showing distribution of p21 or phospho-Rb-S807/811 in G2/M MCF10A (left) or Hs68 (right) cells with either no (“53BP1 foci”, blue) or at least one 53BP1 focus (“53BP1 foci⁺”, red). The distribution of the phospho-Rb and p21 signal in all G2/M cells is shown for comparison (black). Dashed vertical green lines denote the cutoff for calculating the percent p21^high or phospho-Rb^low as in Figure 2; the percentage of cells to the right or left of the green lines is indicated. The number of cells analyzed is the same as in Figure 2A and 2B.

C & D. Probability of a cell having increased p21 or reduced Rb phosphorylation given that it has DNA lesions in G2/M phase. G2/M cells were first classified as 53BP1⁺ (red) or 53BP1 (blue) based on the presence or absence of 53BP1 foci, followed by calculation of the fraction of cells with high p21 or low phospho-Rb.

E & F. Probability of a cell having DNA lesions given that it has high p21 or low Rb phosphorylation in G2/M phase. G2/M cells were first classified as p21^high (red) or p21^low (blue), or phospho-Rb^high (blue) or phospho-Rb^low (red), based on the cutoffs marked by dashed lines in (A) and (B), followed by calculation of the fraction of cells with at least one 53BP1 focus.