Transcriptional repressor that acts as a negative regulator of chondrocyte maturation. PLays a role in distal stomach development; required for proper antral-pyloric morphogenesis and development of antral-type epithelium. In concert with GSC, defines the structural components of the middle ear; required for tympanic ring and gonium development and in the regulation of the width of the malleus. Expressed widely in mesoderm at the gastroduodenal junction (at protein level). Expressed in visceral mesoderm and embryonic skeleton. Expression is restricted to immature proliferative chondrocytes during endochondral ossification. During embryogenesis, expressed in a discrete domain within the mandibular component of the first branchial arch and later in the primordia of middle earassociated bones, the gonium and tympanic ring. Belongs to the NK-3 homeobox family.