SMAD7 and renal fibrosis: However, the inhibition of miRNA-503-5p had no effect on age-dependent renal impairment, although the inhibition of miRNA-503-5p had a therapeutic effect on renal fibrosis by inhibiting pro-fibrotic (Smad7–TGF-β1) signaling pathways and glomerulosclerosis by suppressing (Bax/BCL-2 axis) signaling pathways in an in vivo animal model.