This book provides an in-depth knowledge of protein kinases. The aim of this book is to educate readers regarding protein kinases. As regulators of protein function, protein kinases are concerned with the control of cellular functions through complicated signaling pathways, enabling fine tuning of physiological functions. This book is an integrated effort, with contributions from experts in modern science from across the globe. Existing literature is reviewed in this book, and occasionally, new data on the function of protein kinases in different systems is also provided. The implications of these findings in the light of activated protein kinases in genes and biological role, and the role of kinases and phosphatases in host-pathogen interactions are discussed.