– Tumor necrosis factor receptor superfamily member 9(TNFRSF9) is an inducible T cell surface protein belonging to the TNF receptor superfamily. It is a single-pass type I membrane protein which contains 4 TNFR-Cys repeats. The human and mouse proteins share 60% amino acid sequence identity. It is absent from naive T cells, but upregulated and continually expressed following T cell activation. It is a receptor for TNFSF9/4-1BBL, and possibly active during T cell activation. 4-1BB/CD137/TNFRSF9 Protein, Human, Recombinant (aa 24-186, His & Avi), Biotinylated is expressed in HEK293 mammalian cells with C-Avi-6xHis tag. The predicted molecular weight is 27-35 KDa and the accession number is Q07011.