Ionomycin is an effective Ca²⁺ ionopohre that is commonly used to both modify intracellular Ca²⁺ concentrations and to calibrate fluorescent Ca²⁺ indicators when studying the regulatory properties of Ca²⁺ in cellular processes. Ionomycin also transports Pb²⁺ and some other divalent cations, as well as several lanthanide series trivalent cations, at efficiencies that are greater than or equal to those for Ca²⁺.