XBP1 and cholangiocarcinoma: In addition to its role in benign diseases, the ER stress pathway is involved in tumour initiation and progression in pancreatic cancer27 and hepatocellular carcinoma28; in cholangiocarcinoma, a chemotherapeutic drug was shown to inhibit cholangiocarcinoma proliferation and induce caspase-dependent apoptosis through the ATF6 and XBP1 pathway29.