WASP and Mst1 deficiency has a severe effect on the development of bone marrow (BM) B cells. BM cells were labeled with antibodies specific for surface markers of pre-pro- (A), pro- (B), early pre- (C), late pre- (D), immature (E), and recirculating mature B cells (F) and analyzed by using flow cytometry. Shown are representative dot plots (A), the average numbers of BM (B), BM B cells (C), percentages and numbers of B220⁺CD43^– cells (D-E), and B220⁺CD43⁺cells (F-G). (H-I) The average percentages (± standard error of the mean) and numbers of different subsets extracted from BM (n = 8). One-way analysis of variance with the Tukey test was used to perform multiple group comparisons; *P < .01, **P < .001.