Many factors, including hypoxia, infection, and toxins influence the production of EVs. These factors influence their cargo including mRNA, microRNA, proteins, protein aggregates and lipids. The biogenesis of these vesicles also determine their cell surface markers. These include, but are not limited to cell surface molecules such as CD63, CD9, CD81, tumor susceptibility 101 (TSG101), programmed cell death ligand 1 (PDL1), and placental alkaline phosphatase (PLAP). There are numerous downstream effects, including changes in gene expression in target cells, immune activation/suppression, invasion/migration, autophagy, angiogenesis and ER stress.