FAT tumor suppressor homolog 4 (FAT4), also known as cadherin family member 14 (CDHF14), is a 4,924-amino acid protein with 34 extracellular cadherin repeats, It is expressed broadly in fetal brain, infant brain, brain tumor, and colorectal cancer. Saburi et al. (2008) demonstrated that FAT4 regulates vertebrate PCP and that loss of PCP signaling may underlie some cystic diseases in humans.