Lysyl oxidase (LO) expressed by fibrogenic cells initiates crosslinking of collagen and elastin critical for morphogenesis and repair of connective tissues.Recently,we have discovered that a class of mitogenic/angiogenic proteins with basic isoelectric points including basic fibroblast growth factor (bFGF),vascular endothelial growth factor 165 (VEGF 165) and platelet-derived growth factor-AB (PDGF-AB),are substrates of LO.Oxidation of lysine residues by LO purified from bovine aorta in bFGF,PDFG-AB and VEGF165 dramatically reduced their mitogenic potential for normal and tumor cells.Notably,the unique catalytic activity of LO targeted mitogens not only from mammalian cells but also from oncogenic microorganisms.