PROM1 and glioblastoma: It was shown that PROM1-positive GBM cells exhibited stem cell-related traits such as self-renewal, multipotency, and high proliferation potential [27,28] and that as few as one hundred PROM1-positive cells were capable of initiating tumors in immunodeficient mice that closely resembled the original tumors of patients, thus highlighting the remarkable tumorigenicity of these PROM1-positive tumor cells [29].