PROM1 and glioblastoma: We obtained attached GBM populations from all five (n = 5) collected and processed GBM samples GBM subspheres selected by using a CD133+ affinity column showed a higher content (more than 70% in the five samples) of CD133 positive cells (76.3%) (Fig. 1g), which also were visualized by immunofluorescence assay (Fig. 1j, k).