Fatty acids are an integral part of the phospholipids that make up the bulk of the plasma membranes, or cell membranes, of cells. These phospholipids can be cleaved into diacylglycerol (DAG) and inositol trisphosphate (IP) through hydrolysis of the phospholipid, phosphatidylinositol 4,5-bisphosphate (PIP), by the cell membrane bound enzyme phospholipase C (PLC).