XIAP and neoplasm: Since overexpression of Smac/DIABLO was able to sensitise tumour cells against anticancer drug- and TRAIL-induced apoptosis (Zhang et al, 2001; Guo et al, 2002; Ng et al, 2002; Mc Neish et al, 2003), Smac/DIABLO is thought to be a major antagonist of XIAP.