Among these are the angiogenic and tumor-promoting activities of angiogenin (Ang),6–8 the antiviral and neurotoxic activities of eosinophil-derived neurotoxin (EDN)9,10 and the cytotoxic activities of bovine seminal ribonuclease11 and Onconase.12 The use of site-directed mutagenesis and broad-spectrum inhibitors such as ribonuclease inhibitor (RI) protein13 have been invaluable in establishing the links between biological and enzymatic activities. This evidence concerns the gene ANG and neoplasm.