Fig. 7. Deletion of any of the checkpoint-Rad genes leads, in the presence of HU, to elevated levels of ROS and PI staining. The indicated strains were incubated at 25°C for 4 hours with (+) or without (-) 12 mM HU. Then DCDHFDA was added, and incubation was continued for 80 minutes. The cells were stained with PI and analyzed by flow cytometry.