This is a book on the general theme of cell communication and it focused on the structure and function of key receptors and signalling molecules. Current advances in this rapidly growing field are presented by world experts in the field. The book enables the reader to become progressively acquainted with the intricate networks governing in vitro and in vivo signalling mechanisms. Studies are discussed in a pathophysiological or developmental context. The book is rewarding because it assembles contributions from diverse fields such as X-ray crystallography, electrophysiology, biochemistry, cell biology and developmental biology. The work is interesting for both students and lecturers.