The CXCR4 chemokine receptor, which has been closely linked with cancer cell growth, invasion, angiogenesis and metastasis, has been found to be overexpressed in various types of tumor, including breast cancer, ovarian cancer, glioma, pancreatic cancer, prostate cancer, acute myeloid leukemia as compared to normal cells, which show little or no CXCR4 expression (37–39). This evidence concerns the gene CXCR4 and breast cancer.