Effect of B cell-targeted expression of PKCβII on B cell populations in peripheral blood of Eµ-PKCβIItg and wt mice. Single cell suspensions prepared from peripheral blood and bone marrow of Eµ-PKCβIItg and wild type mice were stained with antibodies to B220, IgM, IgD, and CD21 and analyzed by flow cytometry. Quantitative comparisons were then made of the percentage B220+ cells within the following gates (A) IgD+ IgM+/−, and (B) IgDdim IgM+/− for wt and Eµ-PKCβIItg mice as defined by the strategy illustrated in Supplementary Figure 4. Black dots in these graphs refer to wt and homozygous Eµ-PKCβIItg progeny derived from mating heterozygous Eµ-PKCβIItg mice. Red dots refer to wt mice with similar genetic backgrounds (C57BL/6) that are alike in terms of age to the transgenic mice. Statistical analysis for parts (A) (*P = 0.030) and (B) (*P = 0.023) was performed using a Mann–Whitney U test.