In the liver and pancreas, Atf6–/– mice and zebrafish with ATF6 morpholinos demonstrate symptoms like steatosis, fatty liver, β cell loss, obesity, and type 2 diabetes–like features after intraperitoneal tunicamycin injection (7, 20), and high-fat diet feeding (21) when bred with Agouti and Akita diabetes mouse models (21), or when treated with ethanol (22). The gene discussed is ATF6; the disease is obesity due to melanocortin 4 receptor deficiency.