The CXCR4 chemokine receptor has been found to be overexpressed in different tumors, including HCC, breast cancer, ovarian cancer, glioma, pancreatic cancer, prostate cancer, melanoma, cervical cancer, colorectal cancer, small-cell lung carcinoma, acute myeloid leukemia, chronic lymphoblastic leukemia (CLL), B-CLL, and non-Hodgkin’s lymphoma, as compared to normal cells which show little or no CXCR4 expression [19]–[23]. The gene discussed is CXCR4; the disease is central nervous system cancer.