Novel fusion polypeptide ligands that bind Eph family receptors or the Tie-2 receptor are identified, and methods for making the fusion polypeptide ligands in biologically active form are described. Nucleic acids encoding these novel fusion polypeptide ligands enable production of the fusion polypeptide ligands. The method of making the nucleic acids and the fusion polypeptide ligands is broadly applicable to the production of polypeptide ligands in general, resulting in improved affinity and/or increased activity of the ligand when compared to its native form.