PARP-2 mitigates DNA damage accumulation in preleukemic Eμ-Myc pre-B cells. (A) Representative flow cytometric staining profiles of γH2AX in BM pre-B cells derived from mice of the indicated genotypes. (B) Graph depicting the percentage of positive γH2AX cells. Bars represent mean ± SEM obtained from ≥ 5 mice per genotype. (C) Representative microscopic images depicting immunofluorescence staining of γH2AX in fixed BM pre-B cells. Microscopy was performed by using a Leica TCS SP5 confocal microscope. Red indicates γH2AX; blue indicates DAPI. Original magnification: x63. (D) High-throughput microscopy of γH2AX levels per individual nucleus. At least 2000 nuclei were quantified per condition. Horizontal lines represent median values for each genotype. (E) Graph depicting the percentage of cells showing a pannuclear distribution of γH2AX. (F) Representative images showing DNA damage in BM pre-B cells, visualized by alkaline comet assay, from mice of the indicated genotypes. Original magnification: x10. (G) Graph showing the percentage of pre-B cells with comet. An average of 100 cells was scored for each genotype. Bars represent mean ± SEM obtained from 3 mice per genotype from independent experiments. *P < .05, **P < .01. a.u., arbritary units; WT, wild type.