PROM1 and central nervous system cancer: In gliomas, glioma stem cells (GSCs) were described [4, 5] and have been analyzed based on their expression of “stem-cell markers” such as CD133 [5], CD15 [6], and CD44 [7] or their phenotype of “side population” as evaluated by flow cytometry [8], but there has been no consensus on the marker phenotypes of GSCs [3, 9].