Expression of Lyl-1 in BM and E14 FL cells. Expression of Lyl-1 in total, Lin^–, LSK BM, and E14 FL cells from wt and Lyl-1^–/– mice was monitored by measuring β-galactosidase activity. Cells were stained with biotinylated anti-Lin, PE–anti-Sca-1 and APC–anti–c-Kit mAb and streptavidin PE–Cy-7 and were incubated with the FDG substrate. (A) Flow cytometric profiles depicting the intensity of fluorescence in each subpopulation of wt and Lyl-1^–/– BM and E14 FL. (B) Histograms show the percentage of fluorescent cells in each subpopulation of BM from wt, heterozygote, and homozygote mice and of E14 FL cells of Lyl-1^–/– mice. (C) Expression of Lyl-1 during B-cell differentiation in the BM from wt, heterozygote, and homozygote mice. B cells were separated into 3 different populations: pro–B (B220⁺ CD19^–CD43⁺ IgM^–), pre–B (B220⁺ CD19⁺ CD43⁺ IgM^–), and immature B (B220⁺CD19⁺ CD43^– IgM⁺) cells. Histograms represent the percentages of fluorescent cells in each B-cell subpopulation of wt, Lyl-1^+/–, and Lyl-1^–/– BM. (D) Lyl expression was measured by quantitative RT-PCR in pro–B (B220⁺ CD19^–CD43⁺ IgM^–), pre–B (B220⁺ CD19⁺ CD43⁺ IgM^–), and immature B (B220⁺ CD19⁺ CD43^–IgM⁺) cells. Histograms represent the ratio between Lyl-1 and GAPDH mRNA used as a housekeeping gene. (B-C) Mean of 3 independent experiments (*P < .05). Error bars indicate SEM.