MTOR and gastric cancer: Several molecular pathways are known to be involved in gastric carcinogenesis, such as human epidermal growth factor receptor 2 (HER2), HER3, epidermal growth factor receptor (EGFR), hepatocyte growth factor receptor/c-MET, E-cadherin, matrix metalloproteinase, vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR), WNT/β-catenin, fibroblast growth factor receptor, and Akt/PI3K/mTOR, in gastric cancer and other gastrointestinal (GI) malignancies [50].