FGF21 and fibrosis: Next, we further performed hematoxylin–eosin staining and Masson staining to evaluate the effect of FGF21 deletion on renal pathological damage treated with DOCA-salt and confirmed that the extent of DOCA-salt-induced tubule injury and tubulointerstitial fibrosis in FGF21 KO mice were much severe when compared to those in WT controls (Fig. 2e–h).