A wide range of Ca²⁺ signalling systems deliver the spatial and temporal Ca²⁺ signals necessary to control the specific functions of different cell types. Release of Ca²⁺ by InsP₃ (inositol 1,4,5-trisphosphate) plays a central role in many of these signalling systems. Ongoing transcriptional processes maintain the integrity and stability of these cell-specific signalling systems. However, these homoeostatic systems are highly plastic and can undergo a process of phenotypic remodelling, resulting in the Ca²⁺ signals being set either too high or too low. Such subtle dysregulation of Ca²⁺ signals have been linked to some of the major diseases in humans such as cardiac disease, schizophrenia, bipolar disorder and Alzheimer's disease.