SRC-3 is highly expressed in HSCs and is involved in maintaining HSPC pool. (A) qPCR analysis of SRC-3 messenger RNA expression in LSKs, common lymphoid progenitors (CLPs), CMPs, granulocyte monocyte progenitors (GMPs), megakaryocyte erythroid progenitors (MEPs), and lineage⁺ (Lin⁺) cells (for gating strategies, see supplemental Figure 1A) from 8-week-old C57BL/6J mice (n = 3 mice). The relative expression of SRC-3 was compared with that in LSKs. (B) Western blot analysis of SRC-3 expression in LSKs, MPs, and Lin⁺ cells from 8-week-old C57BL/6J mice (n = 5 mice were pooled). (C) Representative flow cytometric plots show the frequency of Lin⁻ cells, MPs, and LSKs in WT and SRC-3^−/− BM. (D) The frequency (left) and absolute number (right) of MPs and LSKs in the BM of WT and SRC-3^−/− mice (n = 8 mice per group). (E-F) Flow cytometric analysis of the frequency of LT-HSCs, short-term HSCs (ST-HSCs), and MPPs in the LSK compartments of WT and SRC-3^−/− BM (n = 7 mice per group). (G-H) Flow cytometric analysis of the frequency of CMPs, GMPs, MEPs, and CLPs in the BM of WT and SRC-3^−/− mice (n = 6 mice per group). **P < .01.