A clinical study combining agents targeting cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4), which is thought to influence Treg function (Peggs et al., 2009; Quezada et al., 2006; Simpson et al., 2013; Wing et al., 2008), and PD-1, which blocks signals that inhibit T cell function, has reported impressive responses in patients with advanced melanoma (Wolchok et al., 2013). The gene discussed is CTLA4; the disease is melanoma.