Rapamycin

Rapamycin 

Rapamycin can be used as a targetted anti-cancer drug and works as a non-competitive enzyme inhibitor. 

Rapamycin binds to the FKBP protein at an allosteric site. The FKBP is bound to an mTOR enzyme and the binding of rapamycin to FKBP changes the shape of the ATP binding site of the mTOR so phosphorylation no longer occurs and the kinase has been inhibited. 

Rapamycin, although very efficient and powerful at targetting cancer, is not used too often due to the cost. One 30ml tube of ointment containing only one rapamycin tablet can cost up to $3000.