The SDF-1α/CXCR4 axis belongs to this class of mediators and recent studies have shown that inhibition of CXCR4 with antibodies, peptide antagonists or siRNA all reduce metastasis in several solid tumors, including breast [8], [36], [37], [38], melanoma [12], [39], pancreas [40], prostate [41] and colon [42] cancers. The gene discussed is CXCR4; the disease is cancer.