We have recently demonstrated the expression of components of the RAS: PRR, ACE, AT1R, and AT2R by the CSCs in different cancer types, including OCSCC of different subsites [47,48], glioblastoma [8], metastatic malignant melanoma to the brain [18] and regional nodes [49], metastatic colon adenocarcinoma [50], and primary HNcSCC [51]. This evidence concerns the gene ACE and cancer.