Figure 1.

Schematic representation of the biogenesis and release of exosomes by eukaryotic cells. Exosomes firstly formed as multivesicular body (MVB) by budding into early endosomes. Several mechanisms including ESCRT, lipids and tetraspanin-dependent, are involved in MVB formation. If MVBs did not target for lysosomal degradation, they may mobilize and fuse with plasma membrane (PM) to release exosomes, depending on Rab family and soluble NSF-attachment protein receptor (SNARE) complexes respectively.