Cell-autonomous role for B-myb in hematopoiesis. Wild-type mice (CD45.1) were transplanted with control or B-mybF/Fcre (CD45.2) whole BM (WBM). (A) Animals transplanted with BM of both genotypes showed nearly equal donor cell contribution at 8–10 wk posttransplant, before pIpC administration. (B) Total number of control and B-myb–deficient CD45.2+ cells in the WBM of recipient animals following treatment with pIpC. (C) Total number of erythroid (TER119+), B- (B220+), T- (CD3+), and myeloid lineage (CD11b+Gr1+) CD45.2+ cells in the BM of recipients transplanted with control and B-myb–deficient BM following pIpC treatment. Total number of control and B-myb–deficient CD45.2+ HSCs (D) and myeloid progenitors (CMPs, GMPs and MEPs) (E) in the BM of recipient animals following treatment with pIpC. All values represent mean ± SEM. n ≥ 3 per population for each genotype. ***P ≤ 0.0005.