PIK3CB and neoplasm: The PI3K pathway was mutated in 46% of the tumours, with mutations in AKT1 (5.1%), PIK3R3 (2.9%), PTEN (1.4%), PIK3CB (1.4%), PIK3CG (1.4%), PIK3CD (1.4%) and PIK3CA that tended to be mutually exclusive (Figure S12).