Endoplasmic reticulum (ER) stress markers, glucose-regulated protein 78 (GRP78) and protein disulfide isomerases (PDI), were significantly increased in in vitro models of PBC and correlated with premature BEC senescence: both conditions were significantly suppressed following a pretreatment with UDCA [89]. The gene discussed is P4HB; the disease is primary biliary cholangitis.