Cellular Signal Processing is intended for use in signal transduction courses for undergraduate and graduate students. It offers a unifying view of cell signaling that is based on the concept of protein interactions acting as sophisticated data processing networks that govern intracellular and extracellular communication. The content is guided by three major principles that are central to signal transduction: the protein network, its energy supply, and its evolution. It includes coverage of all important aspects of cell signaling, ranging from prokaryotic signal transduction to neuronal signaling. It also highlights the clinical aspects of cell signaling in health and disease.