FST and chronic rhinosinusitis without nasal polyps: However, from the differences of the ratios of follistatin/activinA and follistatin/TGF-β1 in tissues and supernatants in CRSsNP and CRSwNP, we can speculate that activin A is more effectively antagonized in CRSwNP than in CRSsNP and that there is an antagonistic effect between follistatin and TGF-β1.