Undersøgelsesresultater tyder på, at sirolimus bindes til det specifikke cytosoliske protein FKPB- 12, og at FKPB 12- sirolimuskomplex hæmmer aktiveringen af det mammale mål for Rapamycin (mTOR), en kritisk kinase for cellecyklusprogression.
Experimental evidence suggests that sirolimus binds to the specific cytosolic protein FKPB-12 and that the FKPB 12-sirolimus complex inhibits the activation of the mammalian Target Of Rapamycin (mTOR), a critical kinase for cell cycle progression.