Among all CSC surface markers, CXCR4, which is a unique receptor for stromal cell -derived factor-1 (SDF-1), has been shown to be particularly important, since the CXCR4/SDF-1 axis mediates the chemo-attractive effects that allow cancer cells to detach, migrate and seed to distal tissue [14–18]. This evidence concerns the gene CXCR4 and cancer.