CD120b, also known as TNFRII or TNFRSF1B, belongs to the TNF receptor superfamily and can interact with ligands TNFalpha and TNFbeta (also known as LTalpha). It is a 75 kD type I transmembrane protein expressed on lymphocytes, monocytes and granulocytes. When present in a heterocomplex with CD120a, it induces the recruitment of anti-apoptotic molecules, c-IAP1 and 2 that possess E3 ubiquitin ligase activity. Mutations in CD120b are associated with TNF-associated periodic syndrome (TRAPS) or periodic fever syndrome.