SMAD3 and Peritoneal Fibrosis: Intraperitoneal administration of gefitinib, an inhibitor of epidermal growth factor receptor, suppresses TGF-β1 expression, phosphorylation of Smad3, STAT3, and nuclear factor-κB (NF-κB), which leads to reduction in peritoneal fibrosis and a number of CD31-positive blood vessels in the model [94].