Cell survival curves after exposure of Ku70i and LVTHM MCF10A cells to X-ray doses ranging from 0 to 6 Gy or neutron doses from 0 to 3 Gy. Cell survival was measured using a crystal violet cell proliferation assay. Log surviving fractions were fitted as a function of dose using the linear quadratic equation. Each data point represents the mean ± SEM of 4 experiments. (A) and (B) show the effect of Ku70/80 knockdown on cell survival for X-rays and neutrons respectively. In (C) and (D) a comparison of the effect of the radiation qualities in cells with wild type levels (LVTHM cells) and lower expression levels of Ku70/80 (Ku70i cells) respectively, is presented.