Regulation of cell migration, invasion and metastasis by IAP proteins and their antagonists.

Inhibitor of apoptosis (IAP) proteins are a family comprised of a total of eight mammalian members that were initially described to act as endogenous inhibitors of caspases. In addition, extensive evidence has been accumulated over the last years showing that IAP proteins can regulate various signal transduction pathways, thereby exerting non-apoptotic functions beyond the inhibition of apoptosis. For example, IAP proteins have been implied in the control of cell motility, migration, invasion and metastasis. However, currently the question is controversially discussed whether or not they positively or negatively control these processes. As small-molecule inhibitors of IAP proteins have entered the stage of clinical evaluation as experimental cancer therapeutics, a better understanding of their various cellular effects will be critical for their rational use in the treatment of human diseases.