Cell biology has made an appreciable impact on the evaluation of physiological and pathophysiological processes leading to a more detailed understanding of the signaling mechanisms by which cells communicate in vivo and in vitro and modify adaptively. By using cell culture models in addition to animal experiments we are now able to better define the overall and the selective potential of drugs. This book is designed to give information on the advantages and limitations and on new aspects and the meaning of cell culture models in pharmaceutical research.