Acts as a transcriptional activator during early development, limiting the extent of mesoderm formation in the gastrula. Binds to DNA via the target sequence 5'-GT[AC]AACA-3', with 5'-GTAAACA-3' being the preferred binding site. At gastrula stage, expressed in both the anterior and posterior endoderm, with endodermal expression persisting into early tailbud stages. Expression is absent in gastrula stage ectoderm. During tailbud stages, expressed in the pharyngeal region, the neural floor plate, the midbrain, hindbrain and in cranial neural crest cells. Expressed in the foregut of hatching larvae. In tadpoles, expressed in the pharyngeal pouches and in other anterior endodermal regions. Within the tadpole nervous system, expressed in the neural floor plate, at high levels in the ventral midbrain and hindbrain, and at lower levels in the spinal cord. Expressed in the adult lung and brain. First detected in early gastrula stage embryos. Abundant at the neurula stage, becoming less abundant at later stages.