Gabbr1^−/−mutants have decreased numbers of LSK progenitors in BM and lymphocytes in PB. (A) Left panel, Representative flow cytometry gates. Right panels, There are comparable numbers of total BM cells from 2 femur and 2 tibias. The number of LSK progenitors, but not HSCs (LSK/CD48⁻/CD150⁺), is reduced in Gabbr1^−/− BM (n = 5 WT vs n = 5 mutants). (B) Left panel, Representative flow cytometry gates for CLP. Right panels, The number of Lin⁻Sca1^lowcKit^lowCD135^highCD127^low (CLP) progenitors, but not CMP (Lin⁻Sca1⁻cKit⁺CD34^highCD16/32^low), is reduced in Gabbr1^−/− BM (n = 5 WT vs n = 5 mutants). (C) WBCs and lymphocytes, but not neutrophils, were reduced in Gabbr1^−/− PB (n = 5 WT vs n = 5 mutants). (D) Percentages of B220⁺, but not CD11b⁺ or Gr-1⁺, cells were reduced in Gabbr1^−/− PB (n = 8 WT vs n = 9 mutants). (E) The analysis of Hardy B-cell fractions in the BM from Gabbr1^+/+ and Gabbr1^−/− mice (n = 3 WT vs n = 3 mutants). Data are represented as mean plus or minus standard deviation (SD) (*P < .05; **P < .01; ***P < .001). Analyses performed at P15 (see also supplemental Figures 3 and 4).