PIK3CA and glioblastoma: It has been found mutations of several genes in GBM including phosphatase and tensin homolog (PTEN), tumor suppressor P53 (TP53), epidermal growth factor receptor (EGFR), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), phosphatidylinositol 3-kinase regulatory subunit alpha (PIK3R1), platelet derived growth factor receptor alpha (PDGFRA), retinoblastoma 1 (RB1), neurofibromin 1 (NF1), gamma-aminobutyric acid receptor subunit alpha-6 (GABRA6), IDH1, mutS homolog 2 (MSH2), mutS homolog 6 (MSH6), mutL homolog 1 (MLH1), and PMS1 homolog 2 (PMS2).