CXCR4 and neoplasm: It has been reported that epidermal growth factor, platelet-derived growth factor, stromal cell-derived factor-1/CXCR4, SCF/c-Kit and vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR) 1 and VEGFR2 may play a role in the tumor-tropic effects [35].