Of the multitude of toxins known and the enormous variety of effects they cause, of particular interest are those that influence signal transduction. Intercellular communication by chemical signals is essential for the functioning of multicellular organisms. Many toxins exert their biological effects by interfering with the signal transduction initiated by these chemicals (hormones, transmitters, growth factors, and other mediators). Up-to-date information is provided by outstanding experts, who discuss the molecular mechanisms involved in the action of many toxins, as well as the use of...