Schematic representation of formation and molecular structure of exosomes. Exosomes are formed by the trafficking of endocytosed proteins to originate the early endosomes through invagination of the plasma membrane. Early endosomes invaginate to generate intraluminal vesicles (ILVs) that are stored inside the multivesicular bodies. These bodies can then fuse with the plasma membrane to generate exosomes which are released into the extracellular space. These exosomes contain proteins, enzymes, nucleic acids (DNA mRNAs, and miRNAs), and lipids. This cargo is surrounded by lipid bilayer membranes which contain some components such as EGFR (epidermal growth factor receptor), LAIR1 (leukocyte-associated immunoglobulin-like receptor 1), Vps4 (Vacuolar protein sorting-associated protein 4), ERK (extracellular-signal-regulated kinase), PLD (phospholipase D), CD14 (cluster of differentiation 14), Snap23 (synaptosomal-associated protein 23b), RAB13 (Ras-related protein Rab-13), PECAM1 (platelet/endothelial cell adhesion molecule 1), FN1 (fibronectin 1), RAB6b (Ras-related protein Rab-6B), Mac-1 (macrophage-1 antigen), CD99 (cluster of differentiation 99), and PS (phosphatidylserine).