In a prospective study of GBM patients, it was demonstrated that CD133+/Ki67+ was a considerable prognostic factor of disease progression and poor clinical outcome.39 High CD133 expression in high-grade oligodendroglial tumours was reported to indicate shorter survival and to be more reliable than histological assessment.13 Although it was postulated that CD133 could not be evaluated so accurately by real-time PCR40 as by IHC, in our hands mRNA CD133 levels had a prognostic impact similar to that of CD133 protein expression in the above studies. The gene discussed is PROM1; the disease is oligodendroglioma.