The invention provides peptide antagonists, such as synthetic collagen peptides. The invention provides antibody antagonists, or functional fragments thereof, that preferentially bind to denatured extracellular matrix components. It additionally provides methods for using the antagonists for inhibiting angiogenesis, tumor metastasis, and other tumor developmental processes, including cell migration, cell adhesion, cell proliferation, and tumor growth and for treating angiogenesis-dependent conditions or collagen-dependent conditions. The application also provides for use of the antagonists as a vaccine for inducing an immune response, immune focusing and induction of antibody responses.