The binding of PD-L1 to the inhibitory checkpoint molecule PD-1 inhibits T lymphocyte proliferation, survival, and effector functions (cytotoxicity and cytokine release), as well as inducing the apoptosis of tumor-specific T-cells and promoting the differentiation of CD4+ T-cells into Foxp3+ regulatory T-cells. Here, PDCD1 is linked to neoplasm.