Because αSMA is also expressed in myoepithelial and endothelial cells, to further determine the relevance of CAF-derived DKK1 during tumor progression, as a complementary approach we crossed Dkk1fl/fl mice with the FSP1 Cre line (referred to as FSP1-Dkk1cKO) to allow deletion of Dkk1 in fibroblasts. Here, DKK1 is linked to neoplasm.