TGFB1 and renal fibrosis: Current studies suggest that TGF-β helps protect mTOR from degradation by inhibiting Deptor (an inhibitor of mTOR) in a Smad-dependent manner, and also activates mTOR1 and mTOR2 by inducing the PI3K/AKT signaling pathway in renal fibrosis (Lieberthal and Levine, 2009; Lieberthal and Levine, 2012; Das et al., 2013).