PROM1 and glioblastoma: We found that 85.0 % of the anaplastic astrocytomas and 75.4 % of the glioblastomas were negative for CD133, which was much lower than that of other studies who found that less than 40 % of anaplastic gliomas and less than 2 % of glioblastomas were negative for CD133 [23, 24].