To study the kinetics of WinterGreen-WAY photolysis under cell culture conditions, calcium response with respect to irradiation time was measured. Light from a 488 nm laser was applied in close proximity to a cluster of cells for various times and fluorescence intensity was measured using ImageJ. A 200ms pulse of high intensity irradiation was found to be sufficient to elicit calcium signaling (Figure ). In the presence of 488 nm irradiation but absence of WinterGreen-WAY, no calcium response was observed.