ACTA1 and Nasal polyposis: Our results suggest that IL-25-induced release of α-SMA, fibronectin, collagen, MMP-1 and MMP-13 from NPDFs is mediated by the combined activation of the MAPK and NF-kB pathways, thereby providing new clues for fibroblast-mediated inflammation by changing the ECM composition in nasal polyps.