Dr. Cohen made his early scientific breakthroughs in the 1950s, when he was at Washington University in St. Louis. His colleague at the time, Rita Levi-Montalcini, had made a seminal discovery of a protein known as nerve growth factor, which stimulated the growth of nerve cells in laboratory mice.
The two scientists identified the chemical properties and molecular structure of nerve growth factor, or NGF, which marked the first time a biochemical agent that controlled cellular growth had been isolated.
“I did the chemistry, she did the biology,” Dr. Cohen told The Washington Post in 1986. “It was a completely collaborative effort.”
After moving to Nashville in 1959 to teach at Vanderbilt, Dr. Cohen continued his research in a small laboratory, assisted only by a technician and one postdoctoral student. He often walked the halls, puffing on a corncob pipe as he devised basic experiments that would have far-reaching and even profound effects.
In perhaps his most significant experiments, he injected proteins from the salivary glands of adult mice into newborn mice. He found that those mice opened their eyes and developed teeth several days sooner than usual.
Dr. Cohen determined that this early development was spurred by a substance similar to NGF, which he called epidermal growth factor, or EGF. In other experiments, he learned that EGF appeared to stimulate growth in other organs throughout the body and also promoted the healing of damaged skin and other cells.
“It was very simple thinking,” he told the New York Times in 1986. “We were speeding up a natural process, and since nature has spent so many millions of years perfecting her processes, it must be of interest to know how we change the normal program.”
Another of Dr. Cohen’s major discoveries was the protein on the cell membrane to which the EGF binds. He called the protein the epidermal growth factor receptor, or EGF receptor.
When the EGF and the receptor proteins interact, or bind, the result is “a signaling cascade from the receptor to the cell nucleus,” Robert J. Coffey, a cancer researcher and onetime colleague of Dr. Cohen’s at Vanderbilt, said in an interview. “It was a foundational discovery. He’s left a very rich legacy in our understanding of precise signaling pathways, and we continue to learn new lessons from his work.”
Mutations in the EGF receptors have been linked with certain forms of lung cancer and brain cancer. Using the building blocks Dr. Cohen put in place, researchers have discovered that EGF receptors can be targeted with specific drugs to inhibit their unchecked growth, holding a possible key to treating cancer and other diseases.
The importance of Dr. Cohen’s and Levi-Montalcini’s research was not fully understood at first. Over time, however, it has become a paradigm for scientists studying cellular development and seeking possible treatments for cancer, dementia, burns and other maladies.
“The idea is it gives an inkling as to what controls cell growth,” Dr. Cohen said in 1986. “A cancer cell is a normal cell that’s gone wild. If we don’t even know what goes on in a normal cell, how do we know what makes that one go wild?”
Dr. Cohen and Levi-Montalcini, who died in 2012, shared the 1986 Nobel Prize in physiology or medicine.
“On our own we were good and competent,” Dr. Cohen said of their experimental work. “Together we were marvelous.”
Stanley Cohen was born Nov. 17, 1922, in Brooklyn. His father was a tailor, his mother a homemaker.
Dr. Cohen, who had polio as a child, walked with a limp throughout his life. He graduated in 1943 from Brooklyn College, which he said he could afford only because the college had free tuition at the time.
He received a master’s degree in zoology from Ohio’s Oberlin College in 1945 and a doctorate in biochemistry from the University of Michigan in 1948. He taught at the University Colorado before joining the faculty of Washington University in 1952.
He and Levi-Montalcini, who was denied opportunities to teach and practice medicine in her native Italy because of her Jewish heritage, formed an innovative scientific partnership.
“When we started, we were following a little trail of interesting observations,” Dr. Cohen told the Los Angeles Times in 1986. “We had no expectation it would open up a whole field of research.”
He was named to the National Academy of Sciences in 1980 and was awarded the National Medal of Science in 1986. When Dr. Cohen received the Nobel Prize, Coffey said, nothing changed about his manner, his spartan laboratory or his casual wardrobe.
His marriage to Olivia Larson ended in divorce. Survivors include his wife since 1981, Jan Jordan of Nashville; two children and a stepson from his first marriage; and two granddaughters.
After retiring from Vanderbilt in 2000, Dr. Cohen lived for several years in Arizona, where he was part of program in which scientists mentored elementary and high school students.
“Many new things are found by accident,” he told a student group in 2007. “If you’re prepared to see the accident, you can find it.”
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