Additional studies showed that combined anti-OX40/IL-2c therapy did not affect the accumulation or suppressive activity of CD4+CD25+ regulatory T cells (Fig. 7, Figure S2) demonstrating that effector CD4 and CD8 T cells are required for promoting tumor regression and enhanced long-term survival following dual anti-OX40/IL-2c immunotherapy. The gene discussed is CD4; the disease is neoplasm.