In the 1950s, she found a protein in the human nervous system, that she later named the NGF. She worked with Biochemist Stanley Cohen at Washington University, who was able to find the chemical structure of NGF and produce NGF antibodies. Levi-Montalcini's and Cohen's work was noticed in 1986 when they were awarded the Nobel Prize for physiology or medicine. Levi-Montalcini was the fourth woman to win the Nobel Prize.