Figure 3.

Progression of BrdUrd-labeled cells through the cell cycle following treatment with 4 Gy of γ radiation of asynchronously growing (A) or synchronously growing (B) cells. (A) (Upper) The percentage of BrdUrd-labeled control (0 Gy) or irradiated (4 Gy) HT1080 asynchronous cells in G₂/M and G₁ phases as a function of time after irradiation. (Lower) The percentage of BrdUrd-labeled control (0 Gy) or irradiated (4 Gy) for asynchronous HT1080.6TG cells. The cells were pulsed with BrdUrd, and then the BrdUrd-positive population was followed throughout the cell cycle by FACS analysis gating to consider only the BrdUrd-positive cells. The values reported are the means of two independent experiments. (B) Flow cytometric profiles of BrdUrd-positive synchronized HT1080 or HT1080.6TG cells irradiated in early S (4 Gy) or left untreated (0 Gy). Cells were pulsed with BrdUrd when they were beginning to enter into the S phase and immediately irradiated. Cells were collected every 2 hr over a period of 32 hr and two-color FACS analysis performed gating for BrdUrd-positive cells.