Origins of Growth Factors: NGF and EGF

Abstract

Growing up on the streets of Brooklyn, I remember being interested in how things worked: taking apart an old telephone and the gears of my new 4-speed bicycle was most enjoyable. As a biology major at Brooklyn College in 1945, I was fascinated by embryology. How does an egg turn into a chicken or a frog or a person? My only insight into the problem was the thought that it was necessary to understand the chemical reactions inside the egg and embryo and not simply observe biological structures. I, therefore, became a double major in chemistry and biology (also with the hope of earning a living as a laboratory technician). My first job after graduating was working nights as a bacteriologist in a milk processing plant. One of my professors at Brooklyn College wrote asking whether I was interested in going to graduate school. The college had been sending one student a year to the Biology Department at Oberlin to work as a laboratory assistant while studying for a master's degree. Because Oberlin offered to pay my tuition plus some $300 a semester for living expenses, I jumped at the chance. School and science were both interesting and fun. Upon graduating, I continued my education toward a Ph.D. working as an assistant in the Biochemistry Department of the University of Michigan under Howard B. Lewis. My research involved studying the Krebs urea cycle in the common earthworms that I collected from the university campus. I had been told at Oberlin that the yellow cells surrounding the gut in the worm corresponded to the mammalian liver. I decided to check whether the enzymatic reactions in worms were similar to those in mammals. They were (1). My first “real job” was in the Pediatrics Department at the University of Colorado studying creatine metabolism in premature infants under Harry Gordon. I think he hired me because he was impressed by my ability to stomach tube earthworms. After several years, I decided I needed to learn the then new technique of using radioisotopes in metabolic studies, and I obtained an American Cancer Society fellowship to work in the Radiology Department of Washington University under Martin Kamen where I combined this new knowledge with my interest in embryology. Although fertilized frog eggs and early embryos are impermeable to small molecules (amino acids, phosphates, etc.), sufficient amounts of C14O2 were metabolized by intact eggs and embryos to permit the identification of the radioactive compounds present at various stages of development (2). Upon completion of my fellowship, Dr. Kamen recommended me for a position in the Zoology Department of Washington University in the laboratory of Viktor Hamburger and Rita Levi-Montalcini. This move was critical in determining the direction of my research for the next 40-some odd years: the isolation, structure, and function of the first of the “growth factors,” nerve growth factor (NGF) and epidermal growth factor (EGF).