Thapsigargin is a naturally occurring, cell-permeable plant sesquiterpene lactone that non-competitively inhibits the sarco/endoplasmic reticulum calcium ATPase (SERCA, IC50 ~2-80nM). Effectively increases intracellular calcium levels upon SERCA inhibition, leading to cell activation, increased histamine release from mast cells, and increased cancer cell proliferation. Acts as an anti-inflammatory and induces autophagy in-vivo.