Plays an important role in the regulation of embryonic development, cell proliferation, cell differentiation and cell migration (By similarity). Required for Kupffer's vesicle ciliogenesis (PubMed:19164561). Monomer (By similarity). Homodimer (By similarity). Expressed in Kupffer's vesicle. Morpholino knockdown of the protein causes a dramatic loss of cilia in Kupffer's vesicle. Belongs to the heparin-binding growth factors family.