FIGURE 4.

Wip1 null mice exhibit increased γ-H2AX phosphorylation after IR treatment. A, absence of Wip1 in irradiated mouse tissue increases γ-H2AX phosphorylation. Wild-type, Wip1^−/−, Atm^−/−, and Atm^−/− Wip1^−/− double knock-out mice were exposed to 5 Gy of whole body ionizing irradiation. Six hours after irradiation, spleens were harvested from each mouse and tissue lysates were immunoblotted with the indicated antibodies. B, quantitative analysis of γ-H2AX phosphorylation levels in A. Immunoblot bands were quantitated with NIH ImageJ software. γ-H2AX bands were normalized to the total H2AX bands. The γ-H2AX level in irradiated wild-type tissue (lane 3 in A) was set to 1.0.