CXCR4 has been reported to be upregulated in more than 20 cancers, including ovarian [13], prostate [14], esophageal [15], melanoma [16], neuroblastoma [17], and renal cell carcinoma [18], and plays an important role in the communication of cancer cells with their microenvironment [19,20]. The gene discussed is CXCR4; the disease is cancer.