SDF-1 expression was significantly induced in tumor and stromal cells (Supplementary Fig. 1E), and an expansion of CXCR4-expressing CSCs was detected in PD/S-SCCs generated in immunocompetent mice (Supplementary Fig. 1F–1H), indicating that SDF-1 signaling may be activated in CSCs of advanced tumors independently of the immune status of the mice. This evidence concerns the gene CXCL12 and neoplasm.