A23187 is an ionophore, highly selective for Ca2+, that allows for divalent cations to move across the membranes which are usually impermeable to them. The compound was originally isolated from Streptomyces chartreusensis for use as an antibiotic but has been shown to have weak in vitro antimicrobial activity against fungi and gram positive bacteria. Because of its ability to increase intracellular calcium levels of intact cells, it is used in studies of intracellular Ca2+ mediated events. A23187 has been observed to induce cell activation, differentiation or proliferation. In vitro experimentation has shown A23187 to boost ROS generation and platelet fragmentation.