Resistance to rapamycin: a novel anticancer drug

The macrocyclic lactone rapamycin has an established place as an immune suppressive agent in organ transplantation. However, more recently it has been recognized as an inhibitor of pathways that may be activated during malignant transformation and tumor progression. Thus, increasing interest is being directed to this class of antibiotic as potential antitumor agents. Here we summarize the history, mechanism of action, and mechanisms of resistance to rapamycin.