For example, proteomic analysis of exosomes isolated from maternal plasma by cholera toxin B chain and annexin V binding show that exosomes from preeclamptic patients have a higher expression of serpin peptidase inhibitor (PAI)-1, porphyria cutanea tarda (PCT), S100 calcium-binding protein B (S100b), TGF-β, VEGFR1, natriuretic peptide B (BNP), placental growth factor (PGF) (194, 195). The gene discussed is SERPINE1; the disease is porphyria cutanea tarda.