IAP proteins: blocking the road to death's door

The 'inhibitor of apoptosis' (IAP) gene family, which was discovered less than a decade ago, encodes a group of structurally related proteins that, in addition to their ability to suppress apoptotic cell death, are involved in an increasing number of seemingly unrelated cellular functions. Here, we review the functional and structural properties of this fascinating group of proteins, and of several recently identified IAP-binding factors that regulate IAP function.