FunctionProtects against apoptosis induced by TNF or by chemical agents such as adriamycin, etoposide or staurosporine. Suppression of apoptosis is mediated by activation of MAPK8/JNK1, and possibly also of MAPK9/JNK2. This activation depends on TAB1 and NR2C2/TAK1. In vitro, inhibits caspase-3 and proteolytic activation of pro-caspase-9. Isoform 1 blocks staurosporine-induced apoptosis. Isoform 2 blocks etoposide-induced apoptosis.
Tissue specificityIsoform 1 and isoform 2 are expressed at very low levels or not detectable in most adult tissues. Detected in adult heart, placenta, lung, lymph node, spleen and ovary, and in several carcinoma cell lines. Isoform 2 is detected in fetal kidney, heart and spleen, and at lower levels in adult brain, skeletal muscle and peripheral blood leukocytes.
Sequence similaritiesBelongs to the IAP family. Contains 1 BIR repeat. Contains 1 RING-type zinc finger.
Cellular localizationNucleus. Cytoplasm. Nuclear, and in a filamentous pattern throughout the cytoplasm.