In the absence of BAFFR (TNFSF13C) ligation to BAFF (TNFSF13B) ligand, NFkB-inducing kinase (NIK) forms a complex with TNF receptor associated factor 3 (TRAF3) and TRAF2 which exists in a preassembled complex with cellular Inhibitor of apoptosis 1 (cIAP1) and cIAP2 in the cytosol. cIAP1/2 targets NIK for degradation by ubiquitylation, there by inhibiting non-canonical NFkB pathway (Vallabhapurapu et al. 2008, Zarnegar et al. 2008). Upon BAFF trimer binding to BAFFR, TRAF3 but not TRAF2 is recruited to the receptor via a 'PVPAT' binding site. This unique feature of BAFFR to recruit TRAF3 instead of TRAF2 is primarily due to its possession of an atypical TRAF-binding sequence (Morrison et al 2005). Following recruitment to BAFFR, TRAF3 undergoes proteasomal degradation, a process which requires TRAF2 and cIAP1/2.