CD274 and gastric cancer: The outcomes of NK cells in the peripheral blood of the mice in each group, along with the in vivo experimental results that matched the in vitro studies, verified that exosomal miR-552-5p derived from GC influences NK cell function via the PD-1/PD-L1 axis, thereby promoting the growth of subcutaneous transplanted tumors, EMT, and distant metastasis of GC cells in nude mice.