RPS6KB1 and Hyperinsulinemia: In fact, it has been shown in the skeletal muscle of healthy men that combined hyperaminoacidemia and hyperinsulinemia increase S6K1 phosphorylation and inhibitory insulin receptor substrate-1 (IRS-1) phosphorylation at Ser312 and Ser636, whereas the mTORC1 inhibitor rapamycin partially inhibits this increase in mTORC1-mediated S6K1 phosphorylation and IRS-1 Ser312 and Ser636 phosphorylation [77].