ATF6 and other upstream factors involved in ER stress signalling such as X-box-binding-protein 1 (XBP1), as well as targets of the response signalling pathway such as BiP (an ER chaperone), C/EBP homologous protein (CHOP) and others have been shown to be upregulated in cells of breast cancers [119], hepatocellular carcinomas [120] and oesophageal adenocarcinomas [121]—all of which are associated with obesity. This evidence concerns the gene XBP1 and obesity due to melanocortin 4 receptor deficiency.