title: Cytosolic free calcium, a key second messenger in cellular activation.
mesh_terms: D002118:Calcium / Q000032:analysis*; D000242:Cyclic AMP / Q000502:physiology; D003600:Cytosol / Q000032:analysis*; D006706:Homeostasis; D006801:Humans
chemical_list: D000242:Cyclic AMP; D002118:Calcium