Otherwise, thioredoxin domain containing 5 (TXNDC5), an ER protein enriched in fibroblasts, is highly up-regulated in fibroblasts from IPF lung/BLM-induced mouse and enhances TGF-β signaling by increasing and stabilizing TGF-beta receptor 1 (TGFBR1), while TGF-β promotes TXNDC5 expression via ATF6 ER stress pathway, forming a positive feedback loop (Lee et al., 2020). Here, TGFB1 is linked to idiopathic pulmonary fibrosis.