Transcription factor that acts synergistically with tal1/scl and gata1 to specify embryonic dorsal mesoderm to a hematopoietic fate. Induces globin gene expression together with fgf. Expression becomes restricted to the ventral blood island (VBI) as the embryo develops. In late neurula and early tailbud embryos, also expressed in the dorsal lateral plate (DLP), the site of definitive hematopoiesis in the tadpole. Expression in the DLP diminishes during tailbud stages. Expressed in circulating blood cells of tadpoles. Also expressed in non-hematopoietic sites, including the tailbud region and the central nervous system of early neurula embryos. Zygotic expression begins after gastrulation at stage 12.5. By bmp-signaling. Inhibition by fgf regulates the timing of hematopoiesis.