To confirm that XRCC2 is highly expressed in cancer cells, we carried out real-time PCR (RT-PCR) to compare XRCC2 mRNA level in several normal cell lines including two human primary fibroblasts (P1-P2), two human mammary epithelial cells (HMEC1 and HMEC2)17,18, and a chemically immortalized HMEC cell line, MCF10A, to XRCC2 expression in a panel of cancer cell lines including HeLa, a human cervical carcinoma cell line, HT1080, a human fibrosarcoma cell line, and four human breast cancer cell lines, MCF7, MDA-MB-231, HCC1954, and T47D. This evidence concerns the gene XRCC2 and breast cancer.