In the brain, a type of cell was discovered that does not activate the molecular alarms normally sounded when the genome is damaged. They are the astrocytes, named for their spectacular cellular shape reminiscent of a star. When their differentiation is completed and their maximum functional specialisation attained, astrocytes turn off the genes that are responsible for triggering alarms in the presence of such damage and consequently no longer activate a series of responses related to it. For example they do not undergo programmed cell death if exposed to ionizing radiation, as other cells do. This surprising discovery was made by a group of scientists at IFOM in Milan, led by Fabrizio d’Adda di Fagagna, and is published online today in the authoritative scientific journal Cell Death and Differentiation.