Hbo1 deletion causes a marked reduction in HSCs and progenitor cells, whereas peripheral white blood cell counts are still normal.Hbo1fl/+;CreER and Hbo1fl/fl;CreER mice (n = 3 animals per genotype) were gavaged 3× with tamoxifen (150 mg/kg BW per dose, doses 24 hours apart for the 3 day collection or 48 hours apart for the 7 day collection). Bone marrow was collected 3 days (A-B) or 7 days (C-D) after the first tamoxifen treatment. (A,C) Bone marrow stem cell and progenitor subtypes as indicated and assessed by flow cytometry. (B,D) Peripheral blood analysis (Advia). Data are displayed as mean ± SEM and were analyzed using a 2-tailed Student t test. Detailed flow cytometry gating strategies are displayed in supplemental Figure 1. Results using a different cre-recombinase transgene, Mx1-Cre, are displayed in supplemental Figure 3.