To assess potential sources of TGF-β signaling in nasal polyps, we used a prior transcriptional atlas of sinonasal tissues, identifying basal epithelial cells (EpCs) as a predominant source for transcript encoding TGF-β2, while TGF-β1 was more broadly expressed (Supplemental Figure 4A) (4, 13). This evidence concerns the gene TGFB1 and nasal cavity polyp.