In this study, the expression of the integrin αvβ3 subunit β3 in gastric cancer cell lines SGC-7901, BGC-823, and MGC-803; breast cancer cell lines MDA-MB-231 (high expression) and MCF-7 (low expression); as well as in the normal gastric epithelial cell line GES-1 was determined by western-blot. This evidence concerns the gene IGKV4-1 and breast cancer.