Invivo anti-mouse 4-1BB (CD137) Recombinant mAb

4-1BB (CD137, TNFRSF9) is a 39 kDa inducible costimulatory receptor expressed on activated T, NK, NKT and dendritic cells that, upon engagement by its trimeric ligand 4-1BBL or agonistic antibodies, recruits TRAF1/2 to trigger NF-κB, MAPK and PI3K–Akt signaling cascades, thereby enhancing proliferation, survival, cytokine production and cytotoxicity of CD8⁺ and CD4⁺ T cells and NK cells; its expression is tightly regulated (peaking 24–72 h post-activation and restrained by PD-1/CTLA-4 pathways) and its therapeutic agonism is exploited in immuno-oncology to overcome tumor-induced exhaustion, while antagonists are explored for autoimmune diseases.