A multicellular organism is much more than a cluster of cells `glued' to each other largely because of cell adhesions, which are much more than just a glue. Indeed, several decades of research have exposed cell adhesion as a complex process, mediating specific and dynamically regulated interactions as well as crucial signaling cross-talks between the cell and its environment. In addition to their intrinsic complexity, cell adhesions with different surfaces, formed by different cell types, are highly diversified in their molecular, structural and topological properties. Research into cell adhesion is constantly expanding, because new molecular players, mechanisms and functions are continuously emerging, and novel technologies are allowing us to study them in live cells.

The complexity, diversity and fast progress in the cell adhesion field challenge any attempt to cover the entire topic in a single book. The recent Cell Adhesion, edited by Mary Beckerle, handles these aspects wisely and systematically by focusing separately on two levels of complexity, namely adhesion molecules and cellular adhesion sites. Each chapter in this book is a focused review written by leading researchers and covers one type of adhesion molecule or adhesion site. The first part of the book reviews the structure and function of the major classes of eukaryotic cell adhesion molecule. In Chapter 1, Hansjürgen Volkmer describes the immunoglobulin superfamily cell adhesion molecules (IgCAMs), a large and diverse group of glycoproteins with extracellular Ig-like domains that mediate either cell-cell or cell-matrix adhesions during early development and in the adult. Chapter 2, contributed by Rodger McEver, describes selectins, which are cell-surface lectins mediating the adhesion between leukocytes, platelets and endothelial cells under blood flow in the vascular system. Another major group of cell-cell adhesion molecules is the cadherin family of transmembrane glycoproteins. In Chapter 3, Glenn Radice and Masatoshi Takeichi review the structure and function of classical cadherins, which mediate the homophilic and Ca²⁺-dependent interactions in adherens junctions, and discuss their fundamental roles in cell-fate regulation and development. Integrins, a large family of heterodimeric receptors, are key mediators of cell-matrix adhesions and are involved in cell-cell adhesions. In Chapter 4, Douglas DeSimone and colleagues review the integrin family from historical, structural and functional perspectives.

In addition to the extensively studied IgCAMs, selectins, cadherins and integrins, new types of surface protein are increasingly implicated in cell adhesion. Cell surface heparan sulfate proteoglycans (HSPGs), whose function is just starting to become clear, mediate a variety of cell-cell, cell-matrix and cell-microorganism adhesions, which are reviewed by Merton Bernfield and colleagues in Chapter 5. In Chapter 6, Judith White and colleagues discuss the metalloprotease-disintegrins (ADAMs), a family of transmembrane glycoproteins identified just a decade ago, which mediate cell-cell interactions and have been implicated in various processes, such as myogenesis, neurogenesis and sperm-egg adhesion and fusion. This part ends with Chapter 7, contributed by Susann Brady-Kalnay, which focuses on receptor protein tyrosine phosphatases (RPTPs), an intriguing subgroup of IgCAMs that contain tyrosine phosphatase domains in their intracellular region.

At the cellular level, adhesion occurs mainly at specialized adhesive sites along the plasma membrane where clusters of specific adhesion molecules physically link the extracellular ligands to intracellular structural (usually cytoskeletal) and signaling proteins. The second part of the book describes the molecular organization and function of four main types of such adhesion sites. In Chapter 8, Barry Gumbiner and colleagues review the adherens junction, a major type of cell-cell adhesion site where classical cadherins associate with the actin cytoskeleton, structural proteins and key regulatory proteins such as β-catenin. A major class of cell-matrix adhesion site is focal adhesions, where clusters of matrix-bound transmembranal receptors, mainly of the integrin family, associate with complexes of a large variety of anchor and signaling proteins and, through them, with bundles of actin filaments. In Chapter 9, Lynda Peterson and Keith Burridge review the complex structure of focal adhesions, their dynamic evolution from focal complexes and segregation toward fibrillar adhesions, and the major signaling pathways affecting them or affected by them. Although adherens junctions and focal adhesions are anchored to the actin cytoskeleton, the desmosomes and hemidesmosomes associate primarily with the intermediate filament system and mediate cell-cell or cell-basement-membrane adhesions, respectively. In Chapter 10, Kathleen Green and colleagues discuss these adhesions and their fundamental roles in epithelial tissues. The book ends with Chapter 11, in which Shoichiro Tsukita and colleagues review the tight junctions, which seal between neighboring cells in epithelial or endothelial sheets and function as a selective permeability barrier.

Covering each of the above topics in one review chapter is as challenging as covering cell adhesion in a single book. Wisely, the individual reviews do not attempt to exhaustively go into every irrelevant detail and aspect. Instead, they present a balanced discussion of the fundamental facts, mechanisms and concepts in a logical and didactic manner. It is good that speculative models, which are important for scientific progress but often have a short lifetime, are generally excluded from this book. The text contains many references to classic and recent papers, directing the interested reader to the source of detailed information. The book contains only black and white figures and microscopy images; however, some of the chapters could benefit from showing color images (mainly to highlight the relationships between different components). The inevitable overlap between chapters is usually kept within healthy levels, and cross-references direct the reader to the relevant chapters. Finally, the book is easy to read and has a friendly and coherent style.

In conclusion, this book is highly recommended for anyone who has a basic background in cell biology and wishes to get a broad and illuminating overview on eukaryotic cell adhesion. In addition, it would be a most useful reference book for cell adhesion researchers.