Involved in the maintenance of the midbrain-hindbrain boundary (MHB) organizer. Contributes to a positive-feedback loop of FGF signaling in the MHB, enabling the MHB to exert its role as an organizer for the tectal and cerebellar development. Homodimer. Interacts with fgfr1. Expressed maternally from early cleavage stages until the shield stage. Expressed zygotically in the polster at the bud stage. Expressed in the midbrain-hindbrain boundary (MHB) at 12 hours post-fertilization (hpf). Expressed in the tail bud and the mesenchymal cells of the caudal fin primordia at 26 hpf. By the fibroblast growth factor fgf8 in the MHB. Belongs to the canopy family.