GFAP and glioblastoma: We measured mRNA expression of established stem cell-like markers in GBM, the pentaspanning glycoprotein CD133 (AC133 or prominin-1), the transcription factors OLIG2 and SOX2 (sex-determining region Y-box 2), the intermediate filament NESTIN, the embryonic glycoprotein SSEA-1 (stage-specific embryonic antigen-1), the astrocytic differentiation and intermediate filament gene GFAP (glial fibrillary acidic protein), the neuronal marker βIIITub (βIII-TUBULIN) and the Schwann cell lineage marker MBP (myelin basic protein) in U3031MG/MS (Fig. 2c, d).