PIK3CA and cancer: The most common alterations in the PI3K/Akt/mTOR pathway found in human cancers include activating mutations in PIK3CA, loss of function mutations and deletions in PTEN, amplification and activation of specific PI3K-activating receptor tyrosine kinases like EGFR and HER2, and amplification and gain-of-function mutations in AKT1, AKT2, or AKT3 [30].