In recent years, a new understanding of cell-penetrating peptides has emerged, helping researchers to expand beyond a number of long-held dogmas. In Cell-Penetrating Peptides: Methods and Protocols, expert researchers explore the latest information on cell-penetrating peptides (CPPs), providing insight into the most important and contemporary areas of CPP research. Chapters address the historical background of CPP studies, provide an overview of the growing field of research, investigate methods for testing CPP mechanisms, present a summary of methods that attempt to use properties of CPPs to study biochemical intracellular mechanisms of interaction and signal transduction, and include new ideas for turning CPP-based strategies into drugs. Composed in the highly successful Methods in Molecular Biology series format, each chapter contains a brief introduction, step-by-step methods, a list of necessary materials, and a Notes section which shares tips on troubleshooting and avoiding known pitfalls. Innovative and current, Cell-Penetrating Peptides: Methods and Protocols is an essential guide that allows researchers to study intracellular mechanisms in new ways, and to promote the future development of novel drugs.