CXCR4 and neoplasm: Studies on tumor cell biology indicated that the interaction between C-X-C motif chemokine receptor 4 (CXCR4) and its chemokine ligand 12 (CXCL12; also known as stromal cell-derived factor 1, SDF-1) plays an essential role in cell oncogenesis and development of metastatic lesions in tumor [10].