These mechanisms are part of a complex system of communication that govern basic cellular activities and coordinate the actions of cells. Before researchers can understand the behavior of cells, they must understand cell signaling. The tools of molecular biology have revealed many of the genes and proteins involved in cell signaling. Still lacking, however, is a deep understanding of what regulates the interaction between different molecules. A good analogy is language.
Languages are more than a collection of words.
They also include rules of syntax and grammar. The challenge of cell signaling is deciphering the grammar and syntax of cell communication. All living cells must respond appropriately to their environment, whether they are free-living in the soil or part of a tissue. Indeed, cell communication is necessary for the existence of multicellular organisms. The ability of cells to perceive and correctly respond to their microenvironment is the basis of development, tissue repair, and immunity as well as normal tissue homeostasis.