PROM1 and glioblastoma: iPSC induced with U87MG CSCs CM were found to overexpress CSC-specific markers CD133, CD44, ABCG2 and ABCC2, which confirmed these cells as iPSC-derived glioblastoma stem cells (iPSC-GSCs); these markers are more than monolayer U87MG, as observed (Figure 5D).