PTEN and glioblastoma: Spearman’s test established a significant negative correlation between methylation and mRNA expression of the GSK3β, EGFR, and PIK3AP1 genes in DA (p < 0.05), the AKT1 (p < 0.05), AKT2, AKT3, GSK3β, EGFR, and PTEN (p < 0.001) genes in AA and the EGFR and PTEN genes in GBM (p < 0.05).