Btk^−/−PLCγ2^−/− B cells are arrested at an earlier developmental stage compared with BLNK^−/− B cells. Bone marrow cells from WT, BLNK^−/−, and Btk^−/−PLCγ2^−/− mice were stained for the expression of B220 and Igκ/λ (IgL) (A), and B220⁺IgL⁻ cells were further analyzed for the expression of pre-BCR, CD43, CD25, and MHC class II antigens (B). Numbers indicate percentage of cells in the lymphocyte gate (A), and percentage of B220⁺IgL⁻ cells (B). Figures shown are representative of 4 independent analyses.