In primary renal tubular epithelial cells from Smad3-deficient mice, exogenous TGF-β1 treatment was unable to alter epithelial cell phenotypic characteristics, which resulted in Smad3-deficient mice being protected from tubulointerstitial fibrosis after unilateral ureteral obstruction (UUO) 101. This evidence concerns the gene SMAD3 and Ureteral obstruction.