Motilin is a hormone produced by the gastrointestinal system that stimulates the contraction of smooth muscle in the intestines and stomach. Synonyms for Motilin include MTL, MLN, and gastromotilin. MTL is often used as a shorthand for motilin in scientific literature, while MLN is another name that refers to the same hormone. Gastromotilin is an older term that is still sometimes used to refer to motilin and specifically highlights its role in regulating the motility of the stomach. Other related terms with similar meanings to motilin include Gastrointestinal motility stimulant and Interstitial cells of Cajal, or ICCs.