Regulates chordin (CHRD). May play a role in spatial programing within discrete embryonic fields or lineage compartments during organogenesis. In concert with NKX3-2, plays a role in defining the structural components of the middle ear; required for the development of the entire tympanic ring (By similarity). Probably involved in the regulatory networks that define neural crest cell fate specification and determine mesoderm cell lineages in mammals (By similarity). Belongs to the paired homeobox family. Bicoid subfamily.