Cell-to-Cell communication is crucial for multicellular organisms because it allows organisms to coordinate the activity of their cells. Some cell-to-cell communication requires direct cell-cell contacts and this is mediated by different receptors on their cell surfaces. Members of the immunoglobulin superfamily (IgSF) proteins are some of the cell surface receptors involved in cell-cell recognition, communication and many aspects of the axon guidance and synapse formation-the crucial processes during embryonal development (Rougon & Hobert 2003).
Cells interact with adjacent cells as well as with extracellular matrix in tissues and these interactions are supported by cell junctions. Cell junctions consists of protein complexes and include various cell adhesion molecules (CAMs). Cell junctions are more abundant in epithelial cells and there are three major types of cell junctions: adherens junctions (AJs), tight junctions (TJs), and desmosomes.