TGFB1 and chronic kidney disease: Although, it has been reported that urinary TGF-β1 concentration is increased in CKD cats [62, 63] and is correlated with histopathological evidence of interstitial fibrosis in cats [60], it has also been reported that urinary TGF-β1 shows no significant association with worsening renal function in both humans [61] and cats [60].