SFRP1 and nasal cavity polyp: Interestingly, within the CRS subtypes, there was very high expression of SFRP1 and SFRP2 in CRSsNP (Figure 4B), which suggests that fibroblasts may regulate EpC Wnt signaling in CRS and highlights the possibility that unopposed EpC Wnt signaling may contribute to nasal polyp formation.