TGFB1 and pemphigus foliaceus: Injured epithelial cells prompt the fibrogenic process by releasing TGF‐β1, which is a prototypical profibrotic growth factor and well known for having a pivotal role in inducing EMT.31 We confirmed that reduced protein expression of TSPAN1 and increased protein of TGF‐β1 in mouse model of bleomycin‐induced PF and the lung tissue of patient with PF by immunohistochemically staining and Western blotting (Figure 1B,D‐G).