To elucidate the function of caspase-9 in ALS, XIAP (a mammalian inhibitor targeting caspase−3, −7, −9) and p35 (a baculoviral caspase inhibitor not targeting caspase-9) were administrated in transgenic ALS mouse models, and an attenuation effect on the disease progression was shown only in XIAP-treated mice while the delayed onset effect was only induced by p35, suggesting a critical role of caspase-9 in the development of ALS [92]. Here, XIAP is linked to amyotrophic lateral sclerosis.