CTNNB1 and polyp: Moreover, stimulation of isolated basal cells from both patient populations showed that basal cells from polyp tissue upregulated a 10 times higher number of genes compared to non-polyp tissue (i.e., ethmoid sinus tissue of patients spanning the CRS spectrum) and that levels of Wnt pathway activator CTNNB1 at baseline in polyp tissue could only be reached after IL-4/IL-13 stimulation in non-polyp tissue, indicating intrinsic changes on the epigenetic level (5).