XIAP and melanoma: Remarkably, siRNA for several IAPs (cIAP-1, cIAP-2, XIAP, Apollon, Livin and Survivin) or for Bcl-2 have been used not only in vitro studies with soluble or membrane-bound TRAIL (68,135), but also in vivo in combination with AdhCMV-TRAIL, obtaining increased cell death and reduced tumor volume (136), confirming the importance of these molecules in melanoma resistance to TRAIL-dependent cell death.