What is the definition of elastin?
<answer> Elastin is a fibrous protein which is similar to collagen  with abundant proline, valine, and arginine, and which is formed by cross-linking small globular subunits to lysine residues. <context> elastin A fibrous protein which is similar to collagen (in that one-third of the amino acids are glycine) with abundant proline, valine, and arginine, and which is formed by cross-linking small globular subunits to lysine residues.