In recent years, evidence for cytotoxic CD4+ T cells in tumor eradication has been reported.50 51 Through the use of both adoptive transfer models and the B16 F10 melanoma model, Qui et al51 showed that OX40 mAb stimulation increased GzmB production in CD4+ T cells and that dual co-stimulation with 4-1BB could expand these cells. The gene discussed is CD4; the disease is melanoma.