TGFB1 and chronic kidney disease: Cultured human proximal tubular cells treated with indoxyl sulphate had increased expression of p53, NF-κB, TGF-β, and Smad3, which induced cellular senescence, reduced tubular cell proliferation, and promoted fibrosis [112,113], while a 5/6 nephrectomy model of CKD in rats treated with a resin binder of PBT reduced the levels of indoxyl sulphate and attenuated NF-κB, p53, and TGF-β expression [112].