Inhibitor of bone morphogenetic proteins (BMP) signaling. May play an important role in the dorsoventral patterning of the embryo. Homodimer; disulfide-linked. Detected following the activation of the zygotic genome in a few deep cells of the marginal region of the blastoderm. From the 5-12 somite stage, expression is observed in the dorsal telencephalon and in posterior and ventral parts of the eye field. By the 12-somite stage detected all along the dorsal neural tube from the level of the diencephalon to the caudal spinal cord and this expression persists until 24 hours of development. At the 15-somite stage expression is seen in the midline around the tail bud. Between 15 and 20 hours development dorsal as well as ventral expression is observed in recently formed somites while in more mature somites, detected only ventrally. By 24 hours development expression is limited to the ventral sclerotomal aspect of the caudal somites. Later in development detected in very restricted parts of the CNS. Belongs to the noggin family.