MTOR and hepatocellular carcinoma: Various oncogenic or tumor suppressor proteins and molecular mechanisms contributing to the onset and progression of HCC have been so far characterized, such as the Ras mitogen-activated protein kinase (Ras/Raf/MAPK), the phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) and the Wnt/beta-catenin signaling pathways, the ubiquitin/proteasome degradation and the hedgehog signaling pathway [4].