Activated PI3K catalyses the phosphorylation of phosphatidylinositol (4,5)-bisphosphate (PIP2) into phosphatidylinositol (3,4,5)-trisphosphate (PIP3) [25], which can be reversed by the phosphatase tensin and homologue [26] (PTEN; homozygous deletions and mutations are found in 36% of GBM cases) [21]. Here, PTEN is linked to glioblastoma.