SRC-3^−/−HSCs have intrinsically defective function in reconstitution. (A) Schematic of noncompetitive BMT. An amount of 1 × 10⁶ BM cells (CD45.2) from WT or SRC-3^−/− mice was transplanted into lethally irradiated (10 Gy) WT (CD45.1) -recipient mice. (B) Flow cytometric analysis of the frequency of donor-derived cells (CD45.2) in the PB of CD45.1-recipient mice at 16 weeks after BMT (n = 8 mice per group). (C) Schematic of competitive BMT. (D,F) Representative flow cytometric plots show donor chimerism in (D) primary and (F) secondary recipient mice at 16 weeks after BMT (n = 8 mice per group). (E,G) Lineage distribution of donor-derived (CD45.2) myeloid cells (Gr-1⁺ Mac-1⁺), B cells (B220⁺), and T cells (CD3e⁺) in the PB of (E) primary and (G) secondary recipient mice at 16 weeks after BMT (n = 8 mice per group). (H) Size distribution of 180 single-cell sorted WT and SRC-3^−/− LT-HSC–derived colonies 14 days after methylcellulose culture (n = 4 mice per group). (I) Schematic of reciprocal BMT. (J) The frequency of donor-derived cells (CD45.1) in the PB of WT or SRC-3^−/− (CD45.2) –recipient mice at 16 weeks after reciprocal BMT (n = 8 mice per group). **P < .01.