Abstract: The invention describes antagonists for PDGF. The antagonists contain amino acids, and may be monomers or dimers. Especially preferred are dimers which bind the PDGF receptors, but prevent dimerization of the bound receptors. Dimerization is necessary for PDGF effect, hence the antagonistic effect. Also described are nucleic acid sequences for making the antagonists, as well as cell lines transfected with the material.

Abstract: The invention described PDGF modifiers. These are peptides which are derived from wild type PDGF monomers, and function as either agonists or antagonists. Various uses of these are described, as well as recombinant means of production. PDGF-B agonists comprising amino acids 97-180 of the PDGF-B monomer having the cysteines at amino acid residues 124 and 133 substituted, nucleic acid molecules encoding the agonists, plasmids, transformed host cells, and methods for causing receptor dimerization and autophosphorylation in a cell having PDGF-.beta. receptors on its surface comprising administering the PDGF-B agonist form part of the invention.