CXCR4 and gastric cancer: CXCL12 was increased in GC liver metastasis compared with normal liver tissue, the formation of liver metastasis was reduced when the expression of CXCR4 and CXCR7 was suppressed in GC by a mechanism that may inhibit the CXCR4/7-CXCL12 axis (25, 26).