In vitro experiments on the effects of mouse sarcomas 180 and 37 on the spinal and sympathetic ganglia of the chick embryo.

Discovery of nerve growth factor (NGF). Order of authorship in the original publication: Levi-Montalcini, Meyer, Hamburger.

In 1986 Levi-Montalcini was awarded half of the Nobel Prize in Physiology or Medicine, and Stanley Cohen was awarded the other half "for their discoveries of growth factors."