Figure 5.

PP2A-Tws and PP4 play different roles in the Drosophila G2/M DNA damage checkpoint. Each PIR time represents the mean value from three independent experiments ± SEM. Larvae were irradiated with X ray (10 Gy) and dissected brains were fixed at various PIR times; at least three brains per time examined in each experiment. The MI values reported in the graph are normalized with respect to the MI of untreated brains. Note that (A) tws is required for checkpoint signaling like tefu (ATM) and mei-41 (ATR), while (B) PP4 appears to be dispensable for signaling but necessary for checkpoint recovery. wt, wild type.