Next The extent to which EMT contributes to renal fibrosis remains to be clarified; however, evidence for the role of EMT in renal fibrosis in various renal diseases is emerging. A large proportion of the interstitial fibroblasts in fibrotic kidneys have been reported to originate from proximal tubular cells in an animal model [16] . Clinical studies utilizing human kidney biopsies also suggest that EMT plays a role in the pathogenesis of renal fibrosis [43, 44, 45] . Furthermore, EMT of RTECs was well correlated with declining renal function [43, 45] . The renal fibrosis also involved interstitial infiltration of inflammatory mononuclear leukocytes [3] . Thus, our finding suggested that inflammatory mononuclear leukocytes contributed to renal fibrosis by accelerating EMT of RTECs.