MTOR and hepatocellular carcinoma: Despite the vast variety of receptors to receive the growth signal at cell surface, the major signaling mediators downstream of the most of receptor tyrosine kinases (RTKs) are (i) MAPK/ERK signaling cascade and (ii) phosphoinositide 3-kinase (PI3K)/Akt/Mechanistic target of rapamycin (mTOR) signaling pathway in HCC (13, 14).