The death domain (DD) superfamily of proteins share one or more of the following domains: the DD, DED (death-effector domain), CARD (caspase-recruitment domain) and PYD (Pyrin domain). Each of these domains is characterized by a canonical death domain fold, which consists of a bundle of five or six antiparallel α-helices. As their names suggest, these domains play prominent roles in programmed cell death. ASC2 (apoptosis-associated speck-like protein containing a CARD 2), also known as Pyrin-only protein 1 or PADD-only protein 1, is an 89 amino acid member of the DD superfamily that contains one Pyrin domain. Localized to the cytoplasm, ASC2 interacts with ASC to modulate NF-κB and pro-caspase-1 regulation. ASC2 is predominantly expressed in monocytes, macrophages and granulocytes.