CXCR4 and renal cell carcinoma: If this is indeed the case, then our strategy of targeting the ligand for both CXCR4 and CXCR7 (CXCL12) allowed us to block both the biology of CXCR4 and CXCR7 in vivo, and provided a single-target strategy by which to decrease the metastatic potential of RCC.