簡要描述：CD137 exists on the cell surface as a monomer with a molecular mass of 30 kDa and as a dimer of 55 kDa. Human and mouse CD137 share 60% amino acid identity. CD137 (4-1BB), a member of the tumour necrosis factor receptor superfamily, is a type I transmembrane glycoprotein expressed on the cell surface of activated splenic T cells and thymocytes. The functions of CD137 in T lymphocytes include regulating activation, proliferation and apoptosis. CD137 and CD28 are costimulatory molecules of T