Hbo1 deletion in bone marrow chimeras causes a gradual loss of Hbo1-deleted blood cells. (A-E) One million viable bone marrow donor cells from Hbo1^fl/+;CreER or Hbo1^fl/fl;CreER mice (CD45.2⁺; n = 3 animals per genotype) were transplanted with 0.5 million WT competitor cells (CD45.1⁺) into lethally irradiated C57BL/6 congenic recipients (CD45.1⁺). Sixteen weeks later, when the bone marrow was reconstituted, mice were treated 3× with tamoxifen (150 mg/kg BW per dose, doses 48 hours apart). (A) Experimental design and timeline. (B) Percentage contributions of CD45.2⁺ donor cells to peripheral white blood cells over time. (C) Representative FACS plots of contribution of competitor cells (CD45.1⁺) and donor cells (CD45.2⁺) to peripheral white blood cells 16 weeks after bone marrow transplantation. (D-E) Representative FACS plots and enumeration of the contributions of competitor and donor cells in the HSPC compartments. Percentages of parental gate are indicated on the FACS plots. Data are displayed as mean ± SEM and were analyzed using a 2-tailed Student t test.