PIK3CA and adenocarcinoma: The previous studies have shown that PIK3CA amplification was more frequently observed in squamous cell carcinomas (SCC) than adenocarcinomas (ADC), which was closely associated with increased Akt activity in SCC [12,13], suggesting that PIK3CA amplification, in addition to K-ras and EGFR mutations, may be another major cause of overactivation of PI3K/Akt pathway that promotes lung tumorigenesis.