Figure 4:RASMOL generated structures of protein hormones using RCSB Protein Data Bank (PDB) files (http://www.pdb.org/pdb/home/home.do): (a) Insulin-like growth factor-1 (1 polypeptide chain of 70 residues) PDB reference 1GZR. (b) Human insulin (2 polypeptide chains A 21 residues & B 30 residues) PDB reference 3I3Z. (c) Human growth hormone (1 polypeptide chain of 191 amino acid residues,) PDB reference 1HGU.