The linker region preceding BIR2 of XIAP is responsible for the inhibition of caspase‑3 and ‑7, which is further stabilized by interaction with the BIR2 domain itself (Scott et al. 2005). Binding of a dimeric SMAC (DIABLO) N‑terminal peptide with the BIR2 domain of XIAP effectively antagonized inhibition of caspase‑7 by XIAP (Wu G et al. 2000; Chai J et al. 2000).