Rapamycin-d₃is intended for use as an internal standard for the quantification of rapamycin by GC- or LC-MS. Rapamycin is an allosteric inhibitor of the mammalian target of rapamycin (mTOR) complex 1 (mTORC1).¹It interacts with FKBP prolyl isomerase 1A (FKBP12) to form a complex that binds to and inhibits the kinase activity of mTORC1. Rapamycin inhibits growth of Rh1 and Rh30 rhabdomyosarcoma cells in serum-free medium, with 50% inhibition observed at concentrations of 0.1 and 0.5 ng/ml, respectively, and increases apoptosis in these cells at 100 ng/ml.²It also induces autophagy in a variety of cell types.¹Rapamycin inhibits IL-2-induced proliferation of IL-2-dependent T cells by 50% when used at concentrations less than 5 pM.³Formulations containing rapamycin have been used as immunosuppressive agents in the prevention of organ transplant rejection.

1.Kim, Y.C., and Guan, K.-L.mTOR: A pharmacological target for autophagy regulationJ. Clin. Invest.125(1)25-32(2015) 2.Hosoi, H., Dilling, M.B., Shikata, T., et al.Rapamycin causes poorly reversible inhibition of mTOR and induces p53-independent apoptosis in human rhabdomyosarcoma cellsCancer Res.59(4)886-894(1999) 3.Kay, J.E., Kromwel, L., Doe, S.E.A., et al.Inhibition of T and B lymphocyte proliferation by rapamycinImmunology72(4)544-549(1991)