Via the New York Academy of Sciences, an overview of some of the significance of the Notch signaling pathway: "In addition to its role as a gatekeeper of development, the Notch signaling pathway has been implicated in a number of disorders, including cancer, prion diseases, and multiple sclerosis. Notch's role in these disorders stems from aberrant activation of the pathway. In brain cancer, the Notch signaling pathway sets off the production of proteins that promote unchecked cell renewal. In prion disease, Notch activation causes atrophy of nerve cell dendrites and uncontrolled growth of other brain cells called astrocytes. In multiple sclerosis, Notch sets off an autoimmune attack against the brain via the overproduction of certain immune cells." If you look back in the Fight Aging! archives, you'll find more on the significance of Notch when working with embryonic stem cells. In order to effectively use stem cells of any stripe in more sophisticated therapies, scientists must gain better control over their differentiation and group behavior.