RAB3D and neoplasm: ,4 Exosomes are widely present in urine, blood, pleural and peritoneal effusions, saliva, bile, semen, and other body fluids but are secreted particularly by tumor cells, which may be related to Rab3D overexpression, Wnt pathway activation, and the acidic tumor microenvironment.5, 6, 7 Recent studies have shown that exosomes, which carry a large number of functional molecules, are a potentially therapeutically exploitable mode of intercellular signaling.