AKT1 and cancer: More notably, mTOR plays an important role in regulating the growth, metabolism and protein synthesis of cancer cells, but even if the activities of PI3K and AKT are inhibited, cancer cells still maintain mTOR activation (Kharas et al., 2008), and this crosstalk and feedback between mTOR and PI3K greatly limit the therapeutic effects of mTOR or PI3K inhibitors.