The cadherins represent a family of Ca2+-dependent adhesion molecules that function to mediate cell to cell binding that is critical for the maintenance of structure and morphogenesis. Cadherins each contain a large extracellular domain at the N-terminus, which is characterized by a series of five homologous repeats, the most distal of which is thought to be responsible for binding specificity. The relatively short C-terminal intracellular domain interacts with a variety of cytoplasmic proteins, including ∫-catenin, to regulate cadherin function. The cadherin superfamily includes cadherins, protocadherins, desmogleins and desmocollins. FAT3 (FAT tumor suppressor homolog 3, also known as CDHF15 or CDHR10, is a 4,589 amino acid single-pass type I membrane protein expressed in ES cells, primitive neuroectoderm, fetal brain, infant brain, adult neural tissues and prostate. Containing thirty-three cadherin domains, four EGF-like domains and one laminin G-like domain, FAT3 may participate in the interactions between neurites derived from specific subsets of neurons during development.