CTLA4 and neoplasm: To accomplish this, tumor cells may rely on anti-inflammatory checkpoint proteins including the programmed cell death receptor-1 (PD-1) and programmed cell death ligand-1 (PD-L1) complex found on T-cells and tumor cells, as well as the cytotoxic T lymphocyte-associated molecule-4 (CTLA-4) present on the surface of activated T-cells that serve to regulate T-cell tolerance under normal circumstances [5].