So a single cell can basically release a chemical. The chemical kill can travel to a different cell and create some type of change in that cell so it can activate that cell or in some cases, it can inhibit that cell. Now, we actually already spoke about one type of communications system. We discussed the nervous system of the human body and the nervous system uses a special type of chemical known as the neurotransmitter in intracellular communication. So the neurotransmitter basically travels over a very short distance basically across the synapse between the neuron and our adjacent cell. And the neurotransmitter basically only binds to specific cells and it creates a very quick and rapid response.