CXCL12 and neoplasm: C-X-C chemokine receptor type 4 (CXCR4) is a receptor of SDF-1α, and the binding of SDF-1α to CXCR4 modulates downstream signaling pathways, resulting in a variety of responses, such as chemotaxis, tumor cell proliferation, distant metastasis, and gene transcription [4,5].