DKK3 and fibrosis: In addition, we investigated the expression of DKK3 in siNENs, as DKK3 has been reported to be involved in the development of renal and cardiac fibrosis (Zeng et al. 2021; Lipphardt et al. 2019), and its role in tumorigenesis has been investigated in various cancers (Kim et al. 2013; Lee et al. 2020).