In recent years, serine proteases and matrix metalloproteinases (MMPs) have gained considerable attention in tumor biology. For most of these proteases, their expression is a reliable indication of ongoing tissue remodeling. This book provides a comprehensive evaluation of the mechanisms of action of proteases and their inhibitors in tumor biology. The first part provides the reader with a selective overview of the molecular biology of serine proteases, MMPs and their physiological inhibitors. The most important proteases and their physiological as well as synthetic inhibitors are evaluated in the most relevant models of experimental and human cancer. The clinical aspects are also taken into account. This volume offers an update on this challenging aspect of cancer treatment, its interest bias, and possible clinical implication.