The 145-2C11 monoclonal antibody reacts with mouse CD3ε which is a 20 kDa transmembrane cell-surface protein that belongs to the immunoglobulin superfamily. The 145-2C11 antibody has been shown to induce T lymphocyte activation, proliferation, and apoptosis in vitro via binding and stimulating the TCR. When used in vivo the antibody is reported to produce T cell activation, anergy, or death.