The main effector pathway by which Tregs work is through expression of CTLA4 (5), and CTLA4 blockade (6) and PD1 blockade (7) have been shown to be efficacious in some patients with melanoma, particularly when used in combination (8, 9), with 61% of patients in the latter study getting a clinically relevant responses. The gene discussed is CTLA4; the disease is melanoma.