This gene is a member of the Antp homeobox family and encodes a nuclear protein with a homeobox DNA-binding domain. It is included in a cluster of homeobox B genes located on chromosome 17. The encoded protein functions as a sequence-specific transcription factor that is involved in development. Increased expression of this gene is associated with colorectal cancer. Mice that have had the murine ortholog of this gene knocked out exhibit an excessive pathologic grooming behavior. This behavior is similar to the behavior of humans suffering from the obsessive-compulsive spectrum disorder trichotillomania.