Glucagon (GCG, GLP-1) is a peptide hormone secreted by pancreatic alpha cells. It plays a key role in glucose metabolism and homeostasis, and regulates blood glucose by increasing gluconeogenesis and decreasing glycolysis. It is a counter-regulatory hormone of insulin, raises plasma glucose levels in response to insulin-induced hypoglycemia. In diabetes, it plays an important role in initiating and maintaining hyperglycemic conditions. Glucagon also has important functions in nutrient homeostasis, enhancing nutrient assimilation through enhanced gastrointestinal function, as well as increasing nutrient disposal. It also inhibits gastric emptying in humans, which may lead to increased gastric distension and contribute to satiety by causing a sensation of fullness. In immunohistochemistry of normal tissue, GCG has cytoplasmic positivity in cells in islets of Langerhans in the pancreas. References: The UniProt Consortium. Nucleic Acids Res. 47: D506-515 (2019); Nucleic Acids Res. 2016 Jan 4;44(D1):D733-45, PMID:26553804;