Baculoviral IAP repeat-containing 5 (survivin). This gene is a member of the inhibitor of apoptosis (IAP) gene family, which encode negative regulatory proteins that prevent apoptotic cell death. IAP family members usually contain multiple baculovirus IAP repeat (BIR) domains, but this gene encodes proteins with only a single BIR domain. The encoded proteins also lack a C-terminus RING finger domain. Gene expression is high during fetal development and in most tumors yet low in adult tissues. Antisense transcripts are involved in the regulation of this gene's expression. At least four transcript variants encoding distinct isoforms have been found for this gene, but the full-length natures of only three of them have been determined.