Serpins, a group of proteins with similar structures, were first identified as a set of proteins able to inhibit proteases. The first members of the serpin superfamily to be extensively studied were the human plasma proteins antithrombin and antitrypsin, which play key roles in controlling blood coagulation and inflammation. Today, over 1000 serpins have been identified, including 36 human proteins, as well as molecules in plants, fungi, bacteria, archaea and certain viruses. Serpins are thus the largest and most diverse family of protease inhibitors. In contrast, a protein kinase inhibitor is an enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation). Protein tyrosine kinases (PTKs) play a key role in the regulation of cell proliferation, differentiation, metabolism, migration and survival. Due to their involvement in various forms of cancer, PTKs have become prominent targets for therapy. This new book gathers the latest research from around the globe in this dynamic field.