Expression of RAD51 and phosphorylated-RPA32, a marker of DNA end resection a decisive step in the initiation of homologous recombination (HR) activity was evaluated in human cancer cell lines—esophageal adenocarcinoma (OE19, FLO-1), breast cancer (MCF7, MDA231, MDA435) and colon cancer (HCT116, HT29) relative to normal cell types (human diploid fibroblasts; human esophageal epithelial cells and human mammary epithelial cells). This evidence concerns the gene RAD51 and cancer.