MTOR and cancer: Among the various natural compounds, curcumin (a polyphenolic compound derived from turmeric Curcuma longa), resveratrol (a stilbenoid compound derived from grapes, berries or peanuts), epigallocatechin-3-gallate (EGCG) (the predominant catechin in green tea) and quercetin (a potent antioxidant flavonoid plant pigment) have been shown to inhibit PI3K/Akt/mTOR and NF-kB pathways, significantly increasing radiotherapy-induced cancer cell death [13,16,17,18,19,20,21,22].