Chordin is an antagonist(拮抗剂) that binds BMP growth factors in the extracellular space, inhibiting binding to cell surface receptors. Chordin establishes a BMP4 activity gradient at gastrula. Another protein, Noggin(头发生素), has similar activity Secreted antagonists diffuse and are used in development to generate morphogen gradients BMP4 +chd Chd or Cerberus Chordal inhibits Fig 5Chordin is an antagonist（拮抗剂）that binds BMP growth factors in the extracellular space, inhibiting binding to cell surface receptors. Chordin establishes a BMP4 activity gradient at gastrula. Another protein, Noggin（头发生素）, has similar activity. Secreted antagonists diffuse and are used in development to generate morphogen gradients. Chordin inhibits Fig. 5