The Multifunctional Nature of Peptide Growth Factors

Abstract

It might seem paradoxical, perhaps even capricious and quixotic, to introduce this first comprehensive treatise on peptide growth factors with a statement that in reality there is no such thing as a peptide growth factor. Indeed, this treatise does concern itself with an extremely potent set of regulators of cell growth, all of which are peptides, many newly discovered. However, at the beginning of these two volumes, it is important to emphasize that all the peptides considered here actually are elements of a complex biological signaling language, providing the basis for intercellular communication in multicellular organisms. Thus, the “peptide growth factors” that are the topic of this treatise in reality are peptide signaling molecules. They often promote cell growth, but they also can inhibit it; moreover, they regulate many other critical cellular functions, such as control of differentiation and many other processes that have little to do with growth itself. Like the symbols or alphabet of a language or code, the meaning of the action of these peptide signaling molecules can only be understood in context with other symbols. Thus, all peptide growth factors act in sets, and to understand their actions, one must always consider the biological context in which they act.