Tumor necrosis factor receptor II (TNF RII) is also known as tumor necrosis factor receptor superfamily member 1B (TNFRSF1B). This protein forms a heterocomplex with TNF RI, mediating the recruitment of two anti-apoptotic proteins c-IAP1 and c-IAP2 with E3 ubiquitin ligase activity. The function of IAPs in TNF receptor signaling is unknown, however c-IAP1 is thought to enhance TNF-induced apoptosis by ubiquitination and degradation of TNF receptor-associated factor 2 (TRAF2), which mediates anti-apoptotic signaling. Knockout experiments in mice showed that the protein plays a role in protecting neurons from apoptosis by stimulating antioxidant pathways.