Fig. 5. Radiation induces more DNA damage foci in Sca1^- cells. (a) Sca1⁺ and Sca1^- cells were sorted directly onto glass slides following irradiation at 4 Gy and immunostained with anti--H2AX (red). Nuclei were stained with DAPI (blue). Bars, 5 µm. (b) There were significantly more DNA-damage foci in the Sca1^- population (4 Gy Sca1⁺ vs Sca1^-, ^*P<0.0001). A minimum of 200-300 cells were counted in each group.