PLAUR and neoplasm: They were stabilized with a layer of polyethylene glycols (PEGs) and covalently conjugated to tumor-targeting peptides: (i) a single-chain variable fragment (ScFv) peptide that recognizes the epidermal growth factor receptor (EGFR); (ii) an amino terminal fragment (ATF) peptide that recognizes the urokinase plasminogen activator receptor (uPAR); and (iii) a cyclic RGD peptides that recognizes the AvB3 integrin receptor.