Studies have found that CXCL12/CXCR4 axis is stimulated under certain pathological conditions, such as hypoxia, inflammation, ischemia, cancer and autoimmune diseases, and CXCL12/CXCR4 axis is involved in mediating cell chemotaxis and metastasis, promoting immune regulation and may finally inducing angiogenesis (10, 11). Here, CXCR4 is linked to cancer.