MicroRNAs (miRNAs) are emerging molecules in the pathogenesis of human diseases. Identification of miRNAs related to renal fibrosis provides clues to find new signaling pathways to fill the gaps between signaling molecules. Li et al. report another new pathway mediated by miR-433 that is induced by transforming growth factor-β1 in mouse models of renal fibrosis. The signaling also makes a positive-feedback circuit loop, which could be translated into new therapeutic targets.