CXCL12 and neoplasm: Stromal cell-derived factor-1α (SDF-1α) is a homeostatic chemokine and expressed in multiple organs; C-X-C chemokine receptor type 4 (CXCR4) is a receptor of SDF-1α, and the SDF-1α/CXCR4 pathway activation modulates the downstream signaling pathway, leading to chemotaxis, anti-apoptosis, tumor cell proliferation, and gene transcription [8,9].