Amino-terminal enhancer of split, also known AES, belongs to the groucho/TLE family of proteins, can function as a homooligomer or as a heteroologimer with other family members to dominantly repress the expression of other family member genes. This protein is expressed predominately in fetal brain, liver, lung, heart and kidney and in adult muscle. In addition, AES can repress NFkB-regulated gene expression and is thought to play an important role in initiating and maintaining cell differentiation events.