– 4-1BB, is also known as CD137, is a type 2 transmembrane glycoprotein receptor belonging to the TNF superfamily.CD137 can be expressed by activated T cells, but to a larger extent on CD8 than on CD4 T cells. In addition, CD137 expression is found on dendritic cells, B cells, follicular dendritic cells, natural killer cells, granulocytes and cells of blood vessel walls at sites of inflammation. 4-1BB/CD137/TNFRSF9 Protein, Human, Recombinant (aa 24-186, hFc & Avi), Biotinylated is expressed in HEK293 mammalian cells with C-hFc-Avi tag. The predicted molecular weight is 45.7 kDa and the accession number is Q07011.