TGFBR1 and pemphigus foliaceus: TGF-β and TGFBR2 binding activates the TGFBR1/ER stress/ATF6 transcriptional pathway to drive TXNDC5 enrichment in lung fibroblasts, which in turn induces fibroblast hyperactivation, proliferation, and ECM enrichment through activation of TGF-β classical (SMAD3) (107) and nonclassical (JNK, ERK, PI3K, p38, MAPK) signaling (108), leading to PF.