MAP2K1 and breast carcinoma: Human breast carcinoma MCF-7 cells exposed similarly to acidic medium showed essentially complete inhibition of mTORC1 and decreased phosphorylation of ERK1/2 at Thr202/Tyr204, MEK1/2 at Ser217/221, especially at pH 6.2 (Fig. 3B), whereas phosphorylation of the mTORC2 substrate AKT was not affected (Fig. 3B).