a method is provided for treating a disease or condition characterized by aberrant epithelial cell proliferation and / or migration . one step of the method can include administering to a mammal an agent which disrupts an isolated protein complex including : insulin - like growth factor i ; an insulin - like growth factor binding protein selected from igfbp - 3 and igfbp - 5 ; and vitronectin ; or which prevents formation of the isolated protein complex , to thereby treat the disease or condition in the mammal . the agent is selected from the group consisting a polypeptide that is distinguished from igf - ii by substitution of at least one amino acid residue , wherein the polypeptide disrupts the isolated protein complex .