CXC chemokine receptor 4 (CXCR4) and its ligand stromal cell-derived factor-1α (SDF-1α, also known as CXCL12) play an important role in cancer growth and dissemination, and CXCR4/SDF-1α is positively correlated with metastasis in many types of cancer including thyroid, lung, ovarian, renal, prostate, breast, pancreatic, gastric and colorectal cancer (3–12). The gene discussed is CXCL12; the disease is cancer.