Rapamycin

Rapamycin is a specific inhibitor of mTOR (mammalian target of Rapamycin). It forms a complex with FKBP12 that binds to and inhibits mTOR. It also exhibits selective signal blocking leading to the activation of p70/85 S6 kinase, which is potentially due to the inhibition of FRAP autophosphorylation or protein kinase activity. Rapamycin is a potent immunosuppressant and it has anticancer activity. It induces autophagy in yeast and mammalian cell lines. It is unique in its ability to inhibit lymphokine induced cell proliferation at the G1 and S phase as well as an irreversible cellular arrest at the G1 phase in S. cerevisae cells. Angiogenesis inhibition is also exhibited, possibly through the inhibition of the Akt pathway. Rapamycin has been used in some endoderm differentiation studies from human embryonic stem cells (hESC).