Antibodies against mammary derived growth inhibitor (MDGI) react with a fibroblast growth inhibitor and with heart fatty acid binding protein.

A polypeptide growth inhibitor, designated as mammary derived growth inhibitor, has previously been purified from lactating bovine mammary glands. Polyclonal rabbit antiserum raised against mammary derived growth inhibitor cross-reacts with bovine heart fatty acid binding protein and bovine peripheral myelin P2 protein. These results are consistent with the observation that the amino acid sequence of mammary derived growth inhibitor showed homology to the sequences of these proteins. In a parallel series of immunoblotting experiments, rabbit anti-mammary derived growth inhibitor also reacted specifically with a fibroblast growth inhibitor purified from the conditioned medium of cultured mouse 3T3 fibroblasts. These data suggest that bovine mammary derived growth inhibitor and mouse fibroblast growth inhibitor may share common structural features and raise the possibility that these growth inhibitors may together define a new family of growth regulatory molecules.