Ablation of Rictor impairs developmental progression at the late stage of B lineage. (A) Excision of Rictor in B lymphoid cells. B lineage cells were purified from the spleen and BM of Vav-Cre Rictor^fl/fl and control mice, and PCR was performed using 2 different sets of primers detecting Rictor of WT (Rictor⁺), conditional (Rictor^fl), and deleted (Rictor^Δ) alleles (upper panels), and for Rictor⁺ and Rictor^fl alleles, respectively (bottom panels). (B-E) BM and spleen cells of 10- to 12-week-old Vav-Cre Rictor^fl/fl (cKO) or control mice (WT) were analyzed using flow cytometry (n = 8 WT vs 8 cKO). (B) Shown are the B220 vs IgM profiles of BM cells in the viable lymphoid gate with frequencies (%) of the indicated subsets. (C) B lineage cell numbers (mean ± standard error of the mean [SEM]) in the BM were calculated from flow analyses after counting cells in each marrow: “total,” B220⁺; “pre/pro,” B220⁺ IgM^-; “immat/mat,” immature/mature, ie, B220⁺ IgM⁺. (D) Flow cytometry of spleen cells in the viable lymphoid gate or further gates as indicated above panels. (E) Shown are mean (± SEM) cell numbers of the indicated subsets in spleen: FO, follicular B cells (B220⁺ AA4.1^- IgM^med CD23^hi); MZ, MZ B cells (B220⁺ AA4.1^- IgM^hi CD23^lo); mature B cells (B220⁺ AA4.1^-); TS, transitional B cells (B220⁺ AA4.1⁺).