FIG. 6.

Inappropriate replicative DNA synthesis after IR leads to prolonged G₂/M accumulation. NBS1-LBI cells with stably introduced empty vector, wild-type Nbs1, or S343A Nbs1 were pulse-labeled with 30 μM BrdUrd 30 min before 6-Gy irradiation, and cells were harvested and analyzed at the indicated time points after IR. (A) The DNA content of cells that had taken up BrdUrd during the pulse period was examined at various times after IR. (B) Quantitation of the percentage of BrdUrd-positive NBS1-LBI cells in G₂/M as a function of time after IR. All results are representative of at least three different experiments. (C) HCC1937 cells transfected with empty vector, wild-type Brca1, or S1423A Brca1 were pulse-labeled with BrdUrd, and evaluations were performed as for panel A. (D) Quantitation of BrdUrd-positive HCC1937 cells in G₂/M as a function of time after IR. All results are representative of at least three different experiments.