FN1 and renal fibrosis: TGFβ1 mediates progressive renal fibrosis by inducing cell cycle arrest [38], and by stimulating the synthesis of several key fibrotic genes, such as those encoding Pai-1, collagens, fibronectin, connective tissue growth factor (CTGF), and tissue inhibitor of metalloproteinases, thus enhancing ECM production while inhibiting its degradation [39, 40].