PIK3CA and liver cancer: Previous studies have demonstrated the critical role of mTOR in HCC.13 In particular, it has been shown that components of mTORC1 and mTORC2, including p-RPS6, p-AKT and Rictor, are upregulated in ~50% of HCC specimens.13, 19 In addition, activation of mTOR has been associated with poor prognosis and early recurrence independent of the underlying etiology of HCC.36 Recently genomic studies demonstrate that mutations in the mTOR pathway, including mTOR and PIK3CA are rather rare in liver cancer.