HCRTR1 and cholangiocarcinoma: The mitochondrial apoptosis was mediated by OX1R and OX2R but only OX1R was expressed in human digestive cancers encompassing colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDAC), liver cancer (CHC), gastric cancer, esophagus cancer and cholangiocarcinoma (CCH) (13).