XIAP and neoplasm: XIAP binding to caspases suppresses the proteolytic degradation which represents the final enforcement of apoptosis, and the knockdown of XIAP expression targetted and silenced by siRNA enhances the apoptosis and sensitivity in tumor cells [27], suggesting that siRNA targetting XIAP could reinforce cell apoptosis and radiation sensitivity of EC cells to radiotherapy with efficient down-regulation of XIAP expression [28].