Figure 1. BMI1 Is Required for the Pro-B Cell to Pre-B Cell Transition.

(A) Representative fluorescence-activated cell sorting (FACS) plots of developing B cells in the bone marrow of indicated mice. Shown is the frequency of each cell population in the bone marrow of indicated animals. Pro-B: B220⁺ CD19⁺ IgM⁻ IgD⁻ ckit⁺ CD25⁻. Pre-B: B220⁺ CD19⁺ IgM⁻ IgD⁻ ckit⁺ CD25⁻. Immature: B220⁺ CD19⁺ IgM⁺ IgD⁻. Mature: B220⁺ CD19⁺ IgM⁺ IgD⁺.

(B) Frequency of indicated cell populations in the bone marrow of animals. Each point represents one animal; the line represents the mean. n = 6 for each genotype.

(C) Frequency of indicated cell type in the peripheral blood of indicated animals. Each point represents one animal; the line represents the mean. n = 6 for Bmi1^+/+ animals; n = 5 for Bmi1^−/− animals.

(D) Frequency of B220⁺ cells in the spleens of indicated mice. Each point represents one animal; the line represents the mean. n = 4 for Bmi1^+/+ animals; n = 7 for Bmi1^−/− animals.

***p < 0.001, **p < 0.01. BM, bone marrow; PB, peripheral blood.

See also Figure S1.