And isozymes are also typically regulated by different types of regulatory molecules, different types of allosteric effectors. So, inside our body we have many different types of cells. And these different types of cells basically exist under slightly different conditions. Yet all these different types of cells have to carry out identical types of reactions. For instance, to see what we mean, let's imagine we have a cardiac muscle cell and a skeleton muscle cell. So we have two different types of cells that are found at two different types of locations.