In the following, we will show analyses of the protein MRE11 [51,52] arrangement in nuclei of two different cell lines (breast cancer cell line MCF-7, skin fibroblast cell line CCD-1059SK) after low LET irradiation with a dose of 2 Gy and during a time course of repair of up to 48 h. The gene discussed is MRE11; the disease is breast cancer.