Slp65 and p53 cooperate as tumor suppressors in pre-B cells. (A) Flow cytometric analysis of total lymphoid fractions in BM (top). Total CD19+ fractions were gated and analyzed for IgM and IgD expression (bottom). Data are displayed as dot plots, and numbers indicate the percentages of cells within the gates and are representative for 4 5-week-old nontumor-bearing mice. (B) Kaplan-Meier tumor-free survival estimates for Slp65−/− mice (n = 36), p53−/− mice (n = 17), and p53−/−Slp65−/− mice (n = 24). (C) Characterization of pre-B cell tumors by flow cytometry. Dot plots for surface SLC and μ H chain expression (top) and dot plots for CD2 and BP-1 expression (bottom) in gated CD19+ cells from tumor samples of Slp65−/− (S99, S100) and p53−/−Slp65−/− (PS23, PS27) mice.