Nobel prize content by Nobel prize winners: The essential role of protein degradation as a regulatory switch in cell physiology has been honored by the 2004 Nobel prize in Chemistry to Aaron Ciechanover, editor of the series, and Avram Hershko, the author of the opening chapter of volume 1. *Broad coverage: Four volumes with more than 50 contributions in total cover all aspects of protein degradation. Each individual volume highlights a different aspect of the field; all four volumes together provide the most comprehensive reference on protein degradation available. *Unmatched expertise: Editors and authors comprise virtually all the top scientists in the field, including the pioneers of protein degradation research.