CXCR4 and neoplasm: Analyses of the gene expression profiles of CXCL12 and its receptors CXCR4 and CXCR7 in a large CRC patient cohort (n = 107) revealed a significant down-regulation of CXCL12 mRNA in tumor tissues compared to matched normal colorectal mucosa, indicating a potential tumor suppressor function of this chemokine.