DNA-binding protein that binds to the 5'-CAAG-3' core sequence. May function as a transcriptional repressor. Seems to act as a transcriptional antagonist of NKX2-5. May play an important role in the development of craniofacial structures such as the eye and ear. At stage 11, expressed in the surface ectoderm surrounding the optic vesicle. At stage 15, expressed in anterior/nasal side of the early retina. At stage 26, during the peak period of ganglion cell genesis, highly expressed in the nasal retina and the lens ectoderm. Belongs to the HMX homeobox family.