As the actions of PD-1 antagonist was based on the pre-requirement that it blocks PD-1/PD-L1 interactions, we detected the expression of PD-L1 on tumor cells and selected those PD-L1-expressing tumor cells to set up the in vitro experimental model and to evaluate the activity of our PD-1 peptide antagonist. The gene discussed is CD274; the disease is neoplasm.