Trefoil Factor 1 (TFF1) belongs to the three structurally related secreted proteins that contain trefoil domains. TFF1 is an approximately 7 kDa peptide that plays an important role in epithelial regeneration and wound healing. It is highly expressed in goblet cells of the gastric and intestinal mucosa and by conjunctival goblet cells. By conserving intrachain disulfide bonds, human TFF1 formed a three-leaved conformation held together.It is a copper-binding protein that can form disulfide-linked homodimers, associate into disulfide-linked complexes with Gastrokine 2, and form non-covalent complexes with the mucin MUC5AC. TFF1 is down-regulated during the progression from gastritis to gastric dysplasia to gastric cancer, although it is up-regulated in breast and prostate cancers.