The present invention provides a crystallized NC1 domain hexamer of Type IV collagen, and methods for making the crystal, wherein the NC1 domain hexamer is crystallized such that the three dimensional structure of the crystallized NC1 domain hexamer can be determined to a resolution of at least 3 .ANG. or better. The present invention also provides a method for designing compounds to inhibit angiogenesis, tumor growth, tumor metastasis, endothelial cell adhesion and/or proliferation, and/or basal lamina assembly, comprising analyzing the three dimensional structure of a crystallized Type IV collagen NC1 domain hexamer produced by the methods of the invention, and identifying and synthesizing compounds that target regions of the NC1 domain that have been identified by the analysis as being important for type IV collagen heterotrimer and hexamer assembly. The present invention also provides novel polypeptides designed by the rational drug design methods of the present invention, based on an analysis of the type TV collagen NC1 hexamer structure disclosed herein.