May act as signaling molecule during development of the midbrain-hindbrain boundary (MHB) organizer, and be involved in patterning of the nervous system. Not expressed during gastrulation. First detected at the 8-somite stage in the ventral region of the MHB and in the anterior somites. At the 14-somite stage, expressed in the anteromedial margins of the somites and in the optic stalks. At 24 hours, expression is lost in the somites but observed in the otic vesicle. At 30 hours, expressed in the hyoid and at 36 hours in the dorsal diencephalon. Belongs to the heparin-binding growth factors family.