1M4U:
reference: Structural basis of BMP signalling inhibition by the cystine knot protein Noggin., Groppe J, Greenwald J, Wiater E, Rodriguez-Leon J, Economides AN, Kwiatkowski W, Affolter M, Vale WW, Belmonte JC, Choe S, Nature 2002 Dec 12;420(6916):636-42. PMID: 12478285

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