Their functions are not defined, but they may protect the mucosa from insults, stabilize the mucus layer, and affect healing of the epithelium.

[6] All three human trefoil factors are lectins that interact specifically with the disaccharide GlcNAc-α-1,4-Gal.

[8] This disaccharide is an unusual glycotope that is only known to exist on the large, heavily glycosylated, mucins in the mucosa.

By cross-linking mucins through the bivalent binding of this glycotope, the trefoil factors are then able to reversibly modulate the thickness and viscosity of the mucus.

[8] TFF1 expression is frequently lost in gastric carcinoma, probably through mechanism of DNA methylation, and it is therefore considered as a tumor suppressor gene.