Silencing TRB3 decreased ERK1/2 activation, followed by decreased mRNA and protein levels of TGF-β1 and collagen type IV in MMCs, so TRB3 may participate in renal fibrosis of DN by upregulating TGF-β1 and collagen type IV in MMCs via ERK MAPK signaling. Here, MAPK3 is linked to liver dysplastic nodule.