This antibody recognizes Livin, both isoform alpha and isoform beta. Human Livin isoform alpha is a 298 amino acid protein. Livin (BIRC7/KIAP) is a member of the family of inhibitor of apoptosis proteins (IAP) and contains a single copy of a baculovirus IAP repeat (BIR) as well as a RING-type zinc finger domain. Some IAP members, like Liven, also have a RING-type finger motif at their carboxyl-terminal which may enhance anti-apoptotic activity. Many RING finger-containing IAPs possess E3 ubiquitin ligase activity, and it has been shown that Liven acts an E3 ubiquitin ligase for targeting the degradation of Smac/DIABLO. Thus degradation of Smac/DIABLO is thought to be a mechanism to enhance Livin anti-apoptotic activity, thereby promoting cell survival. Two splicing variants of Livin, alpha and beta, have been identified. The two isoforms are thought to have different anti-apoptotic properties; however, there are conflicting reports are to whether they actually differ in their biological activities. Liven is expressed at low levels in adult tissues, and relatively higher levels in developmental tissues and in many cancer cells. Certain cancers patients develop autoantibodies against liven and in a number of cancers, Liven is detected only in the tumors but not, or to substantially lower levels, in the corresponding normal adjacent tissue.