The overexpression of various ICPs, including programmed death protein-1 (PD-1) and cytotoxic T lymphocyte antigen-4 (CTLA-4) on T cells and their ligands (PD-L1 and CD80/86, respectively) on cancer cells, is associated with an uncontrolled growth of tumor cells and immune system idleness. The gene discussed is CTLA4; the disease is cancer.