It acted as a secondary messenger molecule. And the cell used the calcium to basically stimulate different types of proteins. The question is, what is it about calcium that actually makes these calcium ions such prevalent and good intracellular secondary messengers? Well, there are two facts, two things about calcium that makes them so prevalent. Number one is our cells can actually easily detect even the smallest changes in calcium mine concentrations inside the cell in a cytoplasm. And number two is calcium mines can actually form very strong interactions with proteins.