This volume deals with the most advanced areas of reactivation of the cell cycle in terminally differentiated cells. Terminally differentiated cells have long been regarded as irreversibly unable to proliferate. However, this view is being overturned, with great implications for both biological knowledge and potential therapeutic applications. The basic science is presented in detail and the potentialities for exploitation in cell replacement therapy and tissue repair are highlighted. For the first time, large parts of this research field are covered in a single resource, contributed by scientists who have given the most to its advancement in recent years. This volume will be valuable for young scientists wishing to enter this field and will serve as an authoritative reference for those already working in it.