PD-1 and PD-L1 checkpoints suppress T-cell activation and anti-tumor responses, while CTLA-4 inhibits initial T-cell activation in lymph nodes by competing with CD28 for B7 ligands on antigen-presenting cells (APCs), thereby fostering anergy and enhancing the function of Tregs [36–39]. The gene discussed is CTLA4; the disease is neoplasm.