Apoptosis, or programmed cell death, is related to many diseases, such as cancer. Apoptosis is triggered by a variety of stimuli including members in the TNF family and prevented by the inhibitor of apoptosis (IAP) proteins. IAP proteins form a conserved gene family that binds to and inhibits cell death proteases. A novel IAP protein was recently identified and designated survivin, apoptosis inhibitor 4 (API4), and TIAP. Survivin/TIAP interacted with the processed form of caspase-3 and inhibited its proteolytic activity. Survivin/TIAP is predominantly expressed in tissues of embryos, transformed cell lines, and many human cancers and lymphomas.