PIK3CA and central nervous system cancer: Despite the increased PIK3CA (encoding the PI3K catalytic subunit α) and AKT3 expression in IDH-mutant glioma, the overall AKT activities were statistically lower than those of IDH-wildtype, as indicated by the mean AKT phosphorylation at Ser-473 and Thr-308 (Figure 2D and 2E).