OLIG2 and glioblastoma: Briefly, proneural GBM is characterized by the alteration of platelet-derived growth factor receptor alpha (PDGFRA) and mutated IDH1 along with higher expression of certain proneural markers (e.g., SRY-related HMG-box genes [SOX], doublecortin [DCX], delta-like canonical Notch ligand 3 [DLL3], achaete-scute family BHLH transcription factor 1 [ASCL1], transcription factor 4 [TCF4] and oligodendrocytic development genes (e.g., PDGFRA, NK2 homeobox 2 [NKX2-2], oligodendrocyte transcription factor 2 [OLIG2] [81,82,83].