The present invention relates to a method for identifying neovascular structures in mammalian tissue, wherein said neovascular structures are identified by the detection of at least one specific protein in said tissue. It also relates to a method for identifying diseases or conditions associated with neovascularization, methods for targeting and/or imaging neovascular structures and methods for targeting diseases or conditions associated with neovascularization. Furthermore, the present invention is directed to the the use of novel and/or known ligands, preferably antibodies, directed against novel and/or known target proteins for identifying tumor cells in mammalian tissue, preferably mammalian kidney tissue, more preferably mammalian vascular kidney tissue. The present invention also relates to novel ligands, preferably antibodies, fusion proteins comprising said ligands or antibodies, pharmaceutical and diagnostic compositions comprising said ligands, antibodies or fusion proteins, diagnostic and therapeutic methods as well as novel proteins and corresponding polynucleotides, vectors and host cells.