Dose response curves of # MN/1000 BN cells 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. MN frequencies (Y) as a function of dose (D) were fitted to a linear-quadratic model Y = c+ αD+ βD2. Each data point represents the mean ± SEM of 2 experiments. The number of micronuclei at doses of 2 and 4 Gy X-rays and doses of 1 and 2 Gy neutrons represents the mean ± SEM of 9 experiments. (A) and (B) show the effect of Ku70/80 knockdown on MN formation 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.