Insulin is produced exclusively by the beta cells in the islets of Langerhans in the pancreas. The level and beta-cell specificity of insulin gene expression are regulated by a set of nuclear genes that bind to specific sequences within the promoter of the insulin gene (INS; MIM 176730) and interact with RNA polymerase to activate or repress transcription. LMX1 is a homeodomain protein that binds an A/T-rich sequence in the insulin promoter and stimulates transcription of insulin.
