PAX9 is a member of the paired box (PAX) family of transcription factors. Members of this gene family typically contain a paired box domain, an octapeptide, and a paired-type homeodomain. These genes play critical roles during fetal development and cancer growth. The specific function of the paired box 9 gene is unknown but it may involve development of stratified squamous epithelia as well as various organs and skeletal elements.Stapleton et al. (1993) isolated a cosmid for PAX9, a novel member of the paired box-containing gene family. They found it to be closely related in its paired domain to PAX1. Wallin et al. (1993) independently cloned the Pax9 gene in the mouse. PAX9 is a member of the same subgroup as Pax1/undulated.