Furthermore, the xenograft tumor-bearing mice models were established, and we proved that knock-down of PD-L1 inhibited Cyclin D1 and CDK2 (P < 0.05, Fig. 5f, g), and Ki67 (Additional file 1: Figure S2), while promoted Caspase-3 and Bax expressions (P < 0.05, Fig. 5h, i) to facilitate cell growth in CR-GC cells in vivo. The gene discussed is MKI67; the disease is gastric cancer.