CXCR4 and esophageal squamous cell carcinoma: Interestingly, CXCL12/CXCR4 has also been reported in ESCC, and the CXCR4 expression level in primary and metastatic foci was significantly higher than that in normal tissues, and the CXCR4 mediated lymphatic metastasis and distant organ metastasis of ESCC.