FAT1, FAT2, FAT3 and FAT4 are human homologs of Drosophila Fat, which is involved in tumor suppression and planar cell polarity (PCP). The atypical cadherin Fat3 ensures that retinal amacrine cells (ACs) develop this unipolar morphology. Fat3 expression was restricted to the nervous system, for example in the brain, it is expressed in a variety of regions and axon fascicles. However, its strongest expression was observed in the olfactory bulb and retina.