Increased expression of MCT1 and MCT4 was observed in MM cell lines after 48 hours of hypoxia...MM cells could however be sensitized to syrosingopine by treatment with metformin, a complex I inhibitor, resulting in apoptosis….Dual inhibition of MCT1 and MCT4 is not sufficient to induce apoptosis in MM cells; however, they can be sensitized to syrosingopine with metformin.