Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

This compound promotes the dephosphorylation and activation of enzyme HMG-CoA to favor cholesterol synthesis and a phenylalanine for leucine substitution at residue B25 results in its "Chicago" variety. Its biosynthesis involves an excision of the C-peptide, and the compound functions by binding to tyrosine kinase receptors on cell surfaces. Sanger's improvement upon the methods of Edman degradation involved its sequencing, and its production occurs primarily in beta cells on the islets of langerhans. For ten points, name this pancreatic counterpart of glucagon used to regulate blood sugar, deficiencies of which are found in sufferers of diabetes.
Science