SMAD2 and chronic rhinosinusitis with nasal polyps: To determine the functional consequences of EpC αVβ6 expression, we conducted histologic assessment of SMAD2/3 phosphorylation within the epithelium, subepithelium, parenchyma, and glandular regions of tissue sections from CRSsNP and CRSwNP donors, normalized by cell density (Supplemental Figure 5).