Protocadherin Fat 1 is a protein that in humans is encoded by the FAT1 gene. This gene is an ortholog of the Drosophila fat gene, which encodes a tumor suppressor essential for controlling cell proliferation during Drosophila development. It is expressed at high levels in a number of fetal epithelia. The protein is a new member of the human cadherin superfamily, a group of integral membrane proteins characterized by the presence of cadherin-type repeats. And it’s important in developmental processes and cell communication.