Layilin (LAYN), a transmembrane protein with a molecular weight of 55 kDa that is homologous to C-type lectin, is present in many cell lines and tissue extracts.LAYN binds specifically to hyaluronic acid, but not to other tested mucopolysaccharides, through its extracellular structural domain, an extracellular matrix component ubiquitously present in most animal tissues and body fluids. It is suggested that LAYN may be involved in the modulation of cellular cortical structures by mediating extracellular matrix-to-cytoskeleton signaling through interactions with different intracellular binding elements.LAYN plays a role in many cellular processes, including cell morphology, adhesion, motility, homeostasis, and signal transduction. In addition, LAYN may play an important role in lung cancer invasion and lymphatic metastasis.