XIAP and malignant colon neoplasm: In addition to numerous studies elucidating the mechanisms of XIAP’s anti-apoptotic function, our recent studies have revealed several non-apoptosis-related functions of XIAP and its RING domain, such as upregulation of Cyclin D1 to promote bladder cancer cell growth [6] and promotion of colon cancer cell invasion via inhibition of RhoGDIα SUMOylation at lys-138 [7].