Importantly, we observed that the tumor cells in the center zone displayed a prominent enrichment of stem cell markers Sox2 and Sox9, but did not express differentiated cell markers Olig2, CC1, S100β, and PDGFRα as observed in oligodendrocytoma and/or astrocytoma (Fig. 6d, e and Supplementary Fig. 7d–f). This evidence concerns the gene SOX9 and astrocytoma (excluding glioblastoma).