4-1BB (CD137) is a costimulatory molecule expressed on the surface of activated T cells and plays a role in T-cell-mediated proliferative response. 4-1BB signal regulates CD28 co-stimulation in the targeted subset cells to favor Th1 development and maintain long-term cell growth. 4-1BB is also expressed on dendritic cells (DCs) and controls the duration, DC-T interaction, and, therefore, immunogenicity. Clone 3H3 antibody is an agonistic antibody that has been shown to stimulate 4-1BB signaling in vivo.
