U73122 is primarily used in biochemical research to study cellular signaling pathways, particularly those involving phospholipase C (PLC). It acts as a potent inhibitor of PLC, an enzyme that plays a critical role in the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG). By inhibiting PLC, U73122 helps researchers investigate the downstream effects of this signaling pathway, including calcium mobilization and protein kinase C (PKC) activation. This makes it a valuable tool in understanding processes such as cell proliferation, differentiation, and immune responses. Additionally, U73122 is used to explore the role of PLC in various diseases, including cancer, inflammation, and neurological disorders, providing insights into potential therapeutic targets.