Proteases are enzymes responsible for degradation of proteins into polypeptides or amino acids. They are involved in regulation of a variety of essential processes, including cell proliferation and differentiation, tissue homeostasis, angiogenesis, stem cell mobilization, hemostasis, blood coagulation, inflammation, immunity, and apoptosis. Agents that block activity of proteases are called protease inhibitors, and a typical example is α1-Antitrypsin (AAT), a serine protease inhibitor with anti-inflammatory, antiapoptotic, and immunomodulatory properties.