Trefoil factors promote restitution of epithelial cells and are abundantly secreted onto the mucosal surface rapidly after mucosal injury.[33] In contrast to the above, genes coding for apoptosis (TGM2, IGFBP3 and DUSP1) were down-regulated in pterygium, reinforcing the over-proliferative tendency in pterygium. This evidence concerns the gene DUSP1 and pterygium.