The protein encoded by this gene is a member of the TNF-receptor superfamily. This receptors can interact with various TRAF family proteins, through which this receptor induces the activation of NF-kappa B and MAPK8/JNK. This receptor and its ligand are important regulators of the interaction between T cells and dendritic cells. This receptor is also an essential mediator for osteoclast and lymph node development. Mutations at this locus have been associated with familial expansile osteolysis, autosomal recessive osteopetrosis, and Paget disease of bone.