Protease research in the era of systems biology.

Proteases are specific modulators of signaling molecules and their underlying pathways in addition to their degradative roles. However, proteases do not act alone, but form cascades, circuits and networks that all dynamically interconnect to form the protease web, which defines the proteolytic potential of a cell or tissue in a defined condition. To describe the protease web and its net activity several novel high-throughput proteomic techniques, in the field termed degradomics, have been developed. Emerging systems biology methods to evaluate the expression, activity and substrate discovery of proteases are presented. Understanding the protease web and its perturbations in pathology will help to develop new therapeutics for the treatment of diseases, such as cancer, arthritis and chronic obstructive pulmonary diseases.