In this study, we show that the mTOR inhibitor rapamycin and the glutamine antagonist 6-diazo-5-oxo-L-norleucine (DON), a glutamine analog that competitively inhibits the action of glutamine, act additively on immune cells and have a therapeutic effect on the arthritis in the SKG mouse model of RA. Here, MTOR is linked to rheumatoid arthritis.