<prompt> Answer this question truthfullyWhat is the role of inositol triphosphate IP3 in the phospholipase C mechanism of cellular signaling, and where does it cause the release of Ca2 from?  <response>: <reason> In the phospholipase C mechanism of cellular signaling, IP3 generated from phosphatidylinositol 4,5-bisphosphate PIP2 causes the release of Ca2 from intracellular stores in the endoplasmic or sarcoplasmic reticulum. 