<p> Epidermal growth factors and transforming growth factors belong to a general class of proteins that share a repeat pattern involving a number of conserved Cys residues. Growth factors are involved in cell recognition and division [<cite idref="PUB00000557"/>]. The repeating pattern, especially of cysteines (the so-called EGF repeat), is thought to be important to the 3D structure of the proteins, and hence its recognition by receptors and other molecules. The type 1 EGF signature includes six conserved cysteines believed to be involved in disulphide bond formation. The EGF motif is found frequently in nature, particularly in extracellular proteins.</p>