XIAP and cancer: Anti-apoptotic proteins such as the Inhibitors of apoptosis proteins (IAP) family (NIAP, cIAP-1, cIAP-2, XIAP, Livin, BIRC6, ML-IAP, ILP2, Survivin) and Bcl-2 family can be overexpressed in cancer cells, and pro-apoptotic proteins such as BAK, BAX and BOK can be suppressed and thus, preventing cancer cells to undergo apoptosis during cancer progression [40].