Figure 5.

Telomere lengths and processing of DNA damage repair in MCF-7 DNA-PKcs knockdown and control cells after irradiation. A, Cells were irradiated with 4 Gy X-ray, and telomere lengths were assessed 0 to 5 days after radiation by a modified real-time PCR approach. Relative data are expressed as mean value versus nonirradiated control. Values are averages from 3 independent experiments. Error bars, SEM. B, Kinetics of DNA damage repair in siRNA MCF-7 and control (mock-transfected) cells after exposure to 4 Gy of X-rays. Quantitative data for the long PCR amplification expressed as total mean intensity versus nonirradiated control. Values are averages from 3 independent experiments. Error bars, SEM; closed symbols, siRNA MCF-7 cells. Open symbols, control MCF-7 cells. *Statistical significant at P < .05. DNA-PKcs, DNA-dependent catalytic subunit of protein kinase; PCR, polymerase chain reaction; SEM, standard error of the mean; siRNA, small interfering RNA.