Answer
Nerve growth factor (NGF), discovered by Rita Levi-Montalcini, is a protein essential for the survival, development, and function of certain neurons. It plays a crucial role in the nervous system by regulating the growth, differentiation, and maintenance of sympathetic and sensory neurons. NGF's discovery has significantly contributed to our understanding of neuron development and has paved the way for potential therapeutic interventions in neurodegenerative diseases and nerve injuries.