Beyond this, we performed a gene-by-gene correlation analysis using the original sequence information extracted from the CGGA and TCGA databases of genotypes and observed that, in GBM cells, POLD4 expression correlated strongly with MES signature gene expression, but negatively correlated with PN gene marker expression (Fig. 1F and Fig. S1D). This evidence concerns the gene POLD4 and glioblastoma.