MTOR and hepatocellular carcinoma: Cancer cell-directed oncogenic signaling pathways for advanced HCC treatment, including agents targeting the endothelial growth factor receptor (EGFR), the fibroblast growth factor receptor (FGFR), PI3K/Aki/mTOR, TGF-β, c-Met, insulin-like growth factor (IGF) signaling and histone deacetylase, have been actively explored.