Figure 4.

Cells expressing wild-type p53 operate the p53-mediated G1 and the G1/S checkpoints. p53-negative CHOC 400 cells were stably transfected with a p53 minigene consisting of wild-type Chinese hamster p53 cDNA cloned into an expression vector (16). A second cell line was stably transfected with the vector only. Asynchronous cultures of each cell line were irradiated with 10 Gy, and samples were taken and prepared for FACS analysis 3 hr (A and B), 6 hr (C and D), or 9 hr (E and F) after irradiation.