Enhancement of cellular survival does not increase pre-B cell leukemia incidence in Slp65-deficient mice. (A) Absolute numbers of pre-B cells (CD19⁺Ig L⁻cμ⁺) per hind leg in the indicated mice. Bars represent average values and the SEM of 9 to 14 animals per genotype. Asterisks indicate significant differences with P < .001 (t test). (B) Flow cytometric analysis of BM lymphoid cells from the indicated mouse groups. Total CD19⁺ B-lineage cells were gated and CD19/cκ profiles are displayed as dot plots. Percentages of cells within the indicated gates are given and data shown are representative of 3 to 4 animals per genotype. (C) Kaplan-Meier tumor-free survival estimates for Btk^−/−Slp65^−/− mice (n = 25) and Bcl-2 Tg Btk^−/−Slp65^−/− mice (n = 7).