In mammalian systems, these peptides are categorized into three structurally and functionally distinct subtypes: trefoil factor 1 (TFF1), which has been implicated in breast cancer progression; trefoil factor 2 (TFF2), characterized by its potent antispasmodic and mucosal protective properties; and trefoil factor 3 (TFF3), predominantly expressed in intestinal goblet cells and exhibiting extensive distribution throughout the intestinal epithelium. The gene discussed is TFF1; the disease is breast cancer.