PTGS2 and chronic rhinosinusitis without nasal polyps: Then, they discovered that mucin 5AC enriched exosomes from CRSwNP patients could increase the expression of cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF), and matrix metalloproteinase-9 (MMP-9) in CRSsNP-derived fibroblasts.