FIG. 7.
DNA-PK-deficient cells are sensitive to DNA-damaging agents. (A) Etoposide sensitivity. For the parental HCT116 (WT) and Ku70+/− cells, 300 cells were seeded on tissue culture plates in duplicate and exposed to the indicated levels of etoposide. For DNA-PKcs+/− and DNA-PKcs−/− cells, 1,000 and 3,000 cells were used, respectively. Cells surviving to form colonies of at least 50 cells after 10 or 15 (DNA-PKcs−/− cells) days were scored. (B) IR sensitivity. For HCT116 WT and DNA-PKcs+/− cells, 300 cells were seeded on tissue culture plates in duplicate and X irradiated at the indicated doses. For DNA-PKcs−/− cells, 3,000 cells were treated similarly. Cells surviving to form colonies of at least 50 cells after ∼10 days were scored. Both profiles show the averages (±standard deviations) of at least two experiments.