May act as a transcriptional activator by promoting terminal differentiation of interneurons in the developing retina. Likely to play a regulatory role in the development of the ventral forebrain. May play a role in craniofacial patterning and morphogenesis. First appears in neural crest cells of the mandibular stream at stage 15. By TS4 (Townsend and Stewart) is active in the migrating neural crest cells of all streams: the mandibular, hyoid, and first and second branchial. Continuously expressed in the branchial arches through TS5 and TS6 and begins to be expressed at the edges of the limb buds at TS6. Detected in cells of the forebrain at stage TS5. Belongs to the distal-less homeobox family.