4-1BB (CD137; TNFRSF9), a receptor of TNFSF9/4-1BBL, belongs to the tumor necrosis factor (TNF) receptor superfamily[1]. 4-1BB is helpful for T cell activation and development, and also induces peripheral mononuclear cell proliferation and migration to the tumor microenvironment[2]. 4-1BB is also involved in enhancing Nrf2 and NF-κB pathway mediated apoptosis of endothelial cells[3]. Mouse 4-1BB protein is a surface glycoprotein with a transmembrane domain (188-208 a.a.). 4-1BB/TNFRSF9 Protein, Mouse (HEK293, Fc, solution) is the extracellular part (V24-L187) of 4-1BB protein, produced by HEK293 cells with C-terminal Fc-tag.