Figure 3.

Diagrammatic representation of an exosome. Exosomes are commonly 30–150 nm in diameter. They are composed of a phospholipid bilayer and originate from intraluminal vesicles and are released into the extracellular space. Cancer cells secrete more exosomes than healthy cells and also contain more microRNA (miRNA) [86] (Greening et al., 2015). Exosomes contain mutated genes (e.g., KRAS and TP53) and lipid rafts (containing high concentrations of cholesterol, glycosphingolipids, and transmembrane proteins (TM)). Glypican-1, which is a cell surface protein, is associated with pancreatic cancer [92] (Melo et al., 2015). Cell surface tetraspanins, e.g., CD82, CD63 and CD81, are commonly used exosome identifiers.