Apoptotic suppressor. Predominantly nuclear. According to PubMed:9372964 it is cytoplasmic. Cells of the T-lymphocyte lineage. Found in both cortical and medullary cells of the thymus. Expressed at relatively high levels also in spleen, bursa, intestine and lung and at very low levels in testis, brain and skeletal muscle. High levels are induced within 4-8 hours of T-cell activation in spleen and thymus. The ring finger is important for its antiapoptotic effect. Belongs to the IAP family.