However, expression and involvement of CXCR4, CCR7, CCR9, CXCR5 and CX3CR1 in various cancers reported by our laboratory and others suggest that the multi-step process of tumor progression and metastasis is regulated by multiple chemokines and their corresponding receptors [7, 8, 10–12, 16–18, 20]. This evidence concerns the gene CXCR4 and cancer.