Which of the following statements about cell adhesion molecules (CAMs) is false?

The statement regarding cell adhesion molecules (CAMs) that is false is that they only consist of cytoplasmic proteins. In reality, CAMs are a diverse group of proteins that span across the cell membrane, and they include extracellular domains that interact with other cells or the extracellular matrix. These proteins are crucial for various biological processes, including cell signaling and the maintenance of tissue structure.

CAMs can be broadly classified into several families, such as cadherins, integrins, and selectins, each containing extracellular regions that are pivotal for their adhesive properties. The cytoplasmic domain of CAMs may interact with the cytoskeleton and signaling proteins, but the adhesive function relies significantly on their extracellular components. This fundamental aspect highlights the multifunctionality and importance of CAMs in tissue architecture and cellular communication.

Additionally, the other options reflect accurate characteristics of CAMs. They do facilitate adhesion between cells, can form rapid and selective interactions, and are known to be relatively weaker than the more robust structures seen in cell junctions, such as tight junctions or desmosomes. Therefore, the understanding of CAMs as proteins that include more than just cytoplasmic components is essential for a comprehensive grasp of their role in cellular biology and tissue engineering.