In STZ-induced DN and db/db mice-associated DN, Smad7 knockout mice develop more severe albuminuria, renal fibrosis (glomerulosclerosis, tubulointerstitial ECM production), and inflammation (macrophage infiltration, expression of inflammatory cytokines such as TNF-α, IL-1β, and MCP-1) [91,92]. This evidence concerns the gene SMAD7 and renal fibrosis.