But, as it turned out, these immortal, antibody-producing cells were useful not only for scientific inquiry, but also as a novel technological instrument for a variety of medical and industrial applications. Indeed, the technology has led to the development of highly specific diagnostic tests; blockbuster anti-cancer drugs such as Rituxan (rituximab), Erbitux (cetuximab), and Herceptin (trastuzumab); and Avastin (bevacizumab), which is widely used to treat both cancer and diseases of the retina that commonly cause blindness.