SMAD2 and pemphigus foliaceus: Given the important role of balance between the Smad2/3 and Smad1/5/8 pathways mediated by TGF-β in the development of PF and the known role of endoglin in regulating TGF-β signaling, we explored how endoglin regulates TGF-β signaling in PMCs exposed to HG and thus exerts an inductive effect on PF in this study.