CD274 and neoplasm: Prior to tumor implantation, we confirmed at the mRNA level that UL23 promotes PD-L1 expression in BGC-823 cells (Mean ± SEM: 2.523 ± 0.2338 in UL23-BGC-823 cells vs. 1.000 ± 0.2425 in Ctrl-BGC-823 cells, P = 0.0107) (Fig. 7G).