FIGURE 2.

The contents of exosomes are proteins, nucleic acids, amino acids, and metabolites. Extracellular components enter the cell through endocytosis and plasma membrane invagination. Plasma membrane buds are formed on the cavity side and fuse with the components of the endoplasmic reticulum, trans-Golgi network, and mitochondria to form early sorting endosomes. Then, the late sorting endosomes modify the cargo and produce and form various intraluminal vesicles and multivesicular bodies (MVB). Among them, some MVBs degrade after fusion with lysosomes. Other MVB can be transported to the plasma membrane to release intraluminal vesicles as exosomes outside the cell through exocytosis.