Nonetheless, inhibition of HO-1 to Wnt ligands may occur via the suppression of macrophage infiltration, as macrophages are not only involved in driving chronic inflammation but also serve as a major source of functionally active Wnt ligands, including Wnt4, Wnt7b, Wnt10a, and Wnt10b.[13] Here, it is the first time to demonstrate that HO-1 suppresses the activation of Wnt/β-catenin in UUO-induced renal fibrosis. This evidence concerns the gene WNT4 and renal fibrosis.