Another tool to repress antitumor immune responses is the expression of immunomodulatory proteins like programmed cell death protein 1 (PD-1), cytotoxic T lymphocyte associated protein 4 (CTLA-4) and lymphocyte activation gene 3 (LAG-3) or their respective ligands in the tumor microenvironment2. The gene discussed is PDCD1; the disease is neoplasm.