MTOR and synovial sarcoma: These study also revealed an increased concentration of leucine, valine and isoleucine in SS, sustaining the importance of a microenvironment availability of these amino acids in the growth and proliferation of T-cells by the activation of the Mechanistic Target of Rapamycin (mTOR).30, 31, 32, 33 Recently described in the salivary glands of pSS patients, mTOR is a serine/threonine protein kinase with two distinct complexes: mTOR Complex 1 (mTORC1) and 2 (mTORC2).34