CXCR4, a seven-transmembrane G-protein-coupled receptor for stromal-cell derived factor-1α (SDF-1α), has been shown to be expressed in human breast cancer cells, and activation of the SDF-1α/CXCR4 axis is important in breast cancer migration and metastasis [66, 67]. This evidence concerns the gene CXCL12 and breast carcinoma.