By adding vascular endothelial growth factor (VEGF) and basic fibroblast growth factor to mimic the tumor microenvironment in the culture medium of endothelial cells, exosome release and the level of miR-503 in exosomes was reduced, resulting in decreased transfer of endothelial cell-derived exosomal miR-503 to the tumor cells. The gene discussed is VEGFA; the disease is neoplasm.