Probable transcription factor. Present in the vegetal pole and marginal zone but not the animal pole of gastrulae and in equal levels in the dorsal and ventral halves of both gastrulae and neurulae. At neurula stage, expressed in the notochord. During tailbud stages, expressed in the foregut, brain, hypocord, neural floor plate and in two lines of cells just dorsal and ventral to the notochord. Expressed in the adult liver. Expression begins at stage 10.25. Levels increase throughout gastrulation before reaching a peak between stages 11.5 and 12. By activin.