In addition, a study undertaken in primary cultured cell lines established from GBM patients provided evidence that, in CD133+ CSC, the chemotherapy-induced resistance is due, at least in part, to the higher expression of anti-apoptosis proteins, including Bcl-2, FLIP and BCL-XL, as well as the inhibitor of apoptosis protein (IAPs) families (XIAP, NAIP and surviving) [24]. This evidence concerns the gene PROM1 and glioblastoma.