Comparison of breast cancer cell lines revealed that RAD51 protein expression was at two fold or higher in 9 of 12 (75%) triple negative cell lines, 1 of 5 (20%) luminal and 2 of 3 (67%) HER2+ breast cancer cell lines when compared to the MCF10A cell line (near normal mammary epithelial cell line derived from a patient with benign fibrosarcoma)(Data not shown). Here, ERBB2 is linked to breast cancer.