Nbea is a positive regulator of HSPC repopulating activity. (A) qRT-PCR of Nbea expression in hematopoietic cells from adult BM, including HSC (Lineage^–SCA-1⁺c-KIT⁺[LSK]CD150⁺CD48^–); MPPs (LSKCD150⁺CD48⁺ [MPP2] and LSKCD150^–CD48⁺ [MPP3/4]); common myeloid progenitors (CMPs; Lineage^–SCA-1^–c-KIT⁺CD32/16^LowCD34⁺); common lymphoid progenitors (CLPs; Lineage^–c-Kit^medSca-1^medCD127⁺); megakaryocyte-erythroid progenitors (MEPs; Lineage^–SCA-1^–c-KIT⁺CD32/16^–CD34^–); granulocyte-myeloid progenitors (GMPs; Lineage^–SCA-1^–c-KIT⁺CD32/16^–CD34^–); granulocytes, (GR-1⁺), B cells (B220⁺), and T cells (CD3⁺). (B) CD45.2⁺ “test” BM-HSPCs were transduced with control or Nbea-shRNAs. mCherry⁺ cells were then sorted and transplanted along with mock-transduced CD45.1⁺ HSPCs at a 1:1 ratio into lethally irradiated CD45.1⁺/CD45.2⁺ recipients within 44 hours after isolation. Recipient PB was examined for >16 weeks after transplant by flow cytometry for CD45.2⁺ mCherry⁺ cells. (Bi) Schematic of competitive transplantation of Nbea-deficient BM-HSPCs. (Bii) Percentage of CD45.2⁺mCherry⁺ PB at 4 to 16 weeks after transplant. (Biii) Frequency of CD45.2⁺mCherry⁺ PB lineages at 4 to 16 weeks after transplant. (Biv) Contribution of CD45.2⁺mCherry⁺ progenitors to BM progenitors. Data in panel B are from 3 experiments; 5 mice per condition per transplant. Data are represented as mean ± standard error of the mean (SEM). ∗P < .05; ∗∗P < .005; ∗∗∗P < .001, relative to recipients of control-shRNA HSPCs.