The NGR peptide (Asn-Gly-Arg) is a specific peptide that has the ability to target aminopeptidase N (CD13), which is upregulated in the angiogenic tumor vasculature and many kinds of tumor cells (e.g., human fibrosarcoma cells HT-1080), with an expression level approximately 10 times higher than that of healthy cells [86,87]. The gene discussed is RTN4R; the disease is neoplasm.