FA can inhibit the TGF-β1/Smad3 signaling pathway by downregulating the phosphorylation of Smad2/Smad3 and can block the TGF-β mediated downstream regulation of epithelial marker E-cadherin, so as to alleviate PF [96,162]. The gene discussed is TGFB1; the disease is pemphigus foliaceus.