Exosomes are vesicles of endocytic original released by many cells.They are formed by membrane budding into the lumen of an endocytic compartment,leading to the formation of multivesicular bodies.Fusion of multivesicular bodies to the plasma membrane leads to the extracellular release of exosomes.Human mast cell release exosomes containing mRNA,miRNA and proteins.These exosomes can be taken up by tumor cells,such as lung cancer cells.However,their potential functional effects on tumor cell are still unknown.