PIK3CA and glioblastoma: The p110α, p110β and p110δ subunits, which make up class IA PI3Ks, are differentially expressed in glioblastoma.85 Mutations in PIK3CA, the gene that encodes p110α, have been described in about 10% of glioblastoma cases.86 Notably, p110β expression has been associated with poor survival in glioblastoma patients and has been shown to promote glioblastoma cell survival and AKT activation in vitro.85 PI3K activation leads to p110-mediated conversion of phosphatidylinositol-4,5-bisphosphate (PIP2) to phosphatidylinositol-3,4,5-triphosphate (PIP3).