XIAP and neoplasm: Of them, c-IAP1 (cellular IAP1), c-IAP2, XIAP (X-linked IAP), NAIP (neuronal apoptosis inhibitory protein) and BRUCE (BIR-repeat-containing ubiquitin-conjugating enzyme)/Apollon are expressed in normal adult tissues, whereas expression of survivin and livin/ML-IAP (melanoma IAP) is limited to tumor tissues.