Figure 4A,B shows that in the explored oligodendroglioma, IDH1 staining was preferentially associated with the OLIG1+ cell population. In contrast, in the studied astrocytoma, the expression of IDH1 was similarly detected in both OLIG1+ and SOX9+ populations (Figure S8A,B). This evidence concerns the gene SOX9 and astrocytoma (excluding glioblastoma).