PARP-2 is required for c-Myc–driven expansion of preleukemic pre-B cells. (A) Representative flow cytometric density plots showing pre-B (CD19⁺B220⁺c-kit⁻IgD⁻IgM⁻), immature (CD19⁺B220⁺c-kit⁻IgD⁻IgM⁺), and mature (CD19⁺B220⁺c-kit⁻IgD⁺IgM⁺) BM B cells from mice of the indicated genotypes. Percentage of cells in the individual subpopulations with regard to each gate is indicated in each quadrant. Values represent the mean of ≥ 8 mice of each genotype. (B) Bar plot displaying total number of BM cells and absolute number of pre-B, immature (ImmB), and mature (MatB) BM B cells. The number of cells in each population was calculated by multiplying the percentage of each population by the total number of BM cells. (C) Representative flow cytometric density plots showing pre-B (CD19⁺B220⁺c-kit⁻IgD⁻IgM⁻), marginal zone (MZ; CD19⁺B220⁺c-kit⁻CD21^highCD23^low), and follicular (FO) B cells (CD19⁺B220⁺c-kit⁻CD21^lowCD23^high) from spleens of mice of the indicated genotypes. Percentage of cells in the individual subpopulations with regard to each gate is indicated in each quadrant. Values represent the mean of ≥ 8 mice of each genotype. (D) Bar plot showing total number of spleen cells and the absolute number of pre-B, MZ, and FO B cells. The number of cells in each population was calculated by multiplying the percentage of each population by the total number of splenocytes. Values represent mean ± SEM of ≥ 8 mice of each genotype. Only P values between groups either containing or not the EμMyc transgene are represented in the graph for clarity. *P < .05, **P < .01. Ig, immunoglobulin; WT, wild type.