Biological Response Mediators and Modulators explains that the behavior of a cell depends upon the absorption of the ligand, the quantity of functional receptors existing for ligand recognition and binding, and the transduction of the signal through successive intercellular events. The book presents such model systems as the low-density lipoprotein (LDL) receptor, the epidermal growth factor receptor, and the insulin receptor. The LDL receptor is a model for a class of surface receptors that facilitate the cellular application of macromolecules through the process of receptor-mediated endocytosis. The book discusses the general characteristics of receptor-mediated endocytosis. Another topic of interest is the property of growth-related cell surface receptors. The section that follows describes the function of these receptors as tyrosine-specific protein kinases, which is related to the protein yields of some viral oncogenes. The amount of receptors in a cell depends upon the rates of synthesis and inactivation. The book will provide valuable insights for scientists, cytologists, students, and researchers in the field of chemistry.