Disturbed B lymphopoiesis in mice lacking NF-κB2/p100. (A) Splenocytes from 3-week-old wild-type, p100^−/−, and nfkb2^−/− mice were analyzed for B220 and IgM expression by flow cytometry. (B) B220 and CD19 expression on bone marrow cells from 3-week-old wild-type, p100^−/−, and nfkb2^−/− mice was analyzed. Numbers indicate mean values plus or minus SD (%) from 5 mice.