Ionomycin is an ionophore produced by the bacterium Streptomyces conglobatus. It is used in research to raise the intracellular level of calcium (Ca) and as a research tool to understand Ca transport across biological membranes. It is also used to stimulate the intracellular production of the following cytokines; interferon, perforin, IL-2, and IL-4 - usually in conjunction with PMA. These cytokines are important in the inflammatory response.