FIGURE 5.

Caspase-2 regulates G₂/M checkpoint following low dose of IR. A and B, SV40-immortalized Casp2^WT, Casp2^KO, Casp2^C320A, and Casp2^S139A MEFs were irradiated (3 Gy), and total cell lysates were prepared at the indicated time following IR and subjected to immunoblotting with an anticleaved caspase-3 antibody (A) and caspase-3 fluoregenic substrate assay (B). C, analysis of G₂/M checkpoint in MEFs showing flow cytometric profiles of mitotic cells before (0 h) and after low dose (4 Gy) of IR at the indicated time points. The cells were fixed, stained for DNA content (PI) and phospho-H3 (FITC), and assessed by flow cytometry. The data were expressed as the average of two experiments and normalized to untreated controls (Cont) of each cell line. PI, Propidium iodide.