Figure 8. A proposed model showing how rapamycin inhibits mSin1 phosphorylation.

Neither mTORC1/S6K1 nor mTORC2/Akt was found to be involved in the regulation of mSin1 phosphorylation. However, silencing mTOR or mLST8 inhibited the phosphorylation of mSin1 as rapamycin did. Thus, we propose that rapamycin may inhibit mSin1 phosphorylation by targeting an unidentified third mTOR complex (mTORC3) that contains at least mTOR and mLST8.