Transcription factors containing a homeodomain play an important role in the organogenesis of vertebrates. Otx3/Dmbx1 is a member of paired class homeodomain transcription factors. Otx3/Dmbx1 represses the Otx2-mediated transactivation in the developing brain by forming heterodimer with Otx2 on the P3C (TAATCCGATTA) sequence in vitro.