The patterning of the central nervous system (CNS) relies on the interaction of multiple signaling molecules, including Shh (sonic hedgehog homolog), Wnt proteins and BMPs (bone morphogenetic proteins), with their antagonists, namely chordin and Noggin. Chordin is a key developmental protein that dorsalizes early vertebrate embryonic tissues by binding to ventralizing TGF-beta-like BMPs and sequestering them in latent complexes. CHRDL1 (Chordin-like protein 1), also known as CHL, VOPT (Ventroptin) or NRLN1 (Neuralin-1), is a 450 amino acid secreted protein that contains three VWFC domains. Functioning in a similar manner to chordin, CHRDL1 binds to BMP-4 and prevents the interaction of BMP-4 with its target receptors, thereby antagonizing BMP-4 activity. Additionally, CHRDL1 is thought to play a role in dorsoventral axis formation, embryonic bone formation and angiogenesis, as well as in the differentiation of neural stem cells.