MAPK3 and plasma cell myeloma: To better understand whether the reduced levels of mTOR and ERK1/2 phosphorylation are directly involved in the anti-myeloma effects of thioredoxin inhibition in bortezomib-resistant myeloma cells, we treated MM.1R-BTZ and RPMI8226/Dox-BTZ-resistant cells with the BTZ+PX12 combination in the absence and presence of various concentration of mTOR activator (MHY1485) or ERK activator (tBHQ).