Nasal irrigation with licorice extract (Glycyrrhiza glabra) in treating nasal polyps by reducing fibroblast differentiation and extracellular matrix production in TGF-β1-stimulated nasal polyp-derived fibroblasts by inhibiting the MAPK/ERK-1/2 pathway – an in vitro and in clinic study. This evidence concerns the gene TGFB1 and nasal cavity polyp.