The functions of microvesicles (MVs) in gastric cancer are less studied compared to other types of extracellular vesicles. Here, the authors report that in Epstein-Barr virus (EBV)-associated gastric cancer (EBVaGC), Olfactomedin 4 protein is enriched in secreted MVs to promote EBVaGC progression by inhibiting the Hippo signaling in tumor cells.