Thapsigargin is widely used in biochemical research as a potent and selective inhibitor of the sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) pump. It induces calcium release from intracellular stores, leading to elevated cytosolic calcium levels, which is a valuable tool for studying calcium signaling pathways in cells. This mechanism makes it particularly useful in investigating apoptosis, as the disruption of calcium homeostasis can trigger programmed cell death. Additionally, thapsigargin is employed in studies related to endoplasmic reticulum stress and the unfolded protein response, providing insights into cellular stress mechanisms and their implications in diseases like cancer and neurodegenerative disorders. Its ability to modulate calcium dynamics also aids in research on muscle physiology and pharmacology.