The gastric cancer MKN74 and MGC803 cell lines, with high and low expression of PD-L1, respectively, were incubated with 5-FU (0, 0.1, 1.0 μg/ml), and then, PD-L1 level was detected at the 24, 48, and 72 h time points. The gene discussed is CD274; the disease is gastric cancer.