MTOR and central nervous system cancer: For example, resveratrol, a naturally occurring polyphenol in a number of plants, has been observed to induce autophagy in ovarian cancer cells and in human U373 glioma cells (6); curcumin induces autophagy by activating the Akt/mammalian target of rapamycin (mTOR)/p70S6 kinase and extracellular signal-regulated kinase (ERK)1/2 signaling pathways (7); and arenobufagin has been reported to induce apoptosis and autophagy in human hepatocellular carcinoma cells by inhibiting the phosphoinositide-3 kinase (PI3K)/Akt/mTOR pathway (8).