SRC-3^−/−HSCs are highly sensitive to cytotoxic stress and irradiation. (A-C) Peripheral (A) white blood cells (WBC), (B) red blood cells (RBC), and (C) BM LSKs from WT and SRC-3^−/− mice after injection with a single dose of 5-FU (n = 6 mice per group). (D) Survival after sequential 5-FU administration (n = 10 mice per group). (E) Distribution of LSKs in WT and SRC-3^−/− BM 24 hours after 6.0 Gy total body irradiation (TBI) (n = 6 mice per group). (F) Flow cytometric analysis of the apoptosis of LSKs from the BM of WT and SRC-3^−/− mice 12 hours after a dose of TBI (6.0 Gy) (n = 5 mice per group). (G) WT and SRC-3^−/− mice were subjected to 2 Gy TBI (n = 5 mice per group). After 3 hours, DNA damage in LSKs was assessed by flow cytometry with γ-H2AX^S139 staining. *P < .05, **P < .01. DAPI, 4′,6-diamidino-2-phenylindole.