TFF1/pS2 is a gastric peptide that is highly expressed by mucosal goblet cells of the stomach, where it is thought to play a role in maintaining the integrity of the epithelial layer of the mucosa through the regulation of cell-cell adhesion and cell migration. Research studies have shown that TFF1 functions as a tumor suppressor in the stomach as its expression is frequently lost in gastric carcinomas, largely due to promoter hypermethylation. Research studies have also demonstrated that TFF1 is a transcriptional target of estrogen receptor-α and that TFF1 expression in breast carcinoma may be used as a predictive biomarker for response to anti-estrogen therapy.