Biochemically, caspase-8 was found to enter the complex of the inhibitor of NF-κB kinase (IKK) with the upstream Bcl10-MALT1 (mucosa-associated lymphatic tissue) adapter complex which were crucial for the induction of nuclear translocation of NF-κB. Moreover, the biochemical form of caspase-8 differed in the two pathways. For the death pathway, the caspase-8 zymogen is cleaved into subunits that assemble to form the mature, highly active caspase heterotetramer whereas for the activation pathway, the zymogen appears to remain intact perhaps to limit its proteolytic function but enhance its capability as an adapter protein.