SOX2 and glioblastoma: Fig 1A shows the H&E staining of tumor 5653 with HGG morphology. We did not observe necrosis in these tumors, suggesting these are HGG and not GBM. All mouse glioma lines show full loss of Nf1 and TP53 as evidenced by the loss of the wildtype Nf1 and Tp53 alleles of the genotyping PCRs (Fig 1B). Finally, these glioma cell lines express the oligodendrocyte precursor cell (OPC) markers SOX2 and NG2 (Fig 1C), consistent with the suspected cell of origin for HGG [19–21].