Probable transcription factor. May be involved in the early anteroposterior patterning of the neuroectoderm. In early gastrulae, expressed in the inner layer of the posterior dorsal ectoderm and in non-involuted mesoderm. By the mid-gastrula stage, expressed solely in the posterior ectoderm. At the end of gastrulation, expressed in ectodermal regions fated to become diencephalon, midbrain and hindbrain, and weakly expressed in regions fated to become spinal cord and tailbud. At the neurula stage, expressed in the midbrain and posterior forebrain (diencephalon) but not in the more anterior forebrain (telencephalon). Also expressed posteriorly in rhombomere 5. At tailbud stages, expression remains in the anterior brain and is also detectable along the length of the central nervous system and in the tailbud. Expression begins in early gastrula stage embryos, peaks at the mid-gastrula stage and remains detectable until late tailbud. By FGF signaling.