The maximum fluorescence intensity induced by WinterGreen-WAY uncaging was less than that of 5 µM WAY-161503, indicating that while the kinetics of the photolysis reaction was fast enough to induce 5HT2C activation, local concentration of the active compound was not equivalent to 5 µM. Importantly, 5HT2C activation was only observed within an approximate 100 µm radius beyond the event of irradiation (Figure ). This provides a high level of spatiotemporal control of activation and could serve as a powerful tool for studying cell-cell communication. Subsequent 200 ms irradiation in the presence of WinterGreen-WAY was able to elicit extended calcium signaling, with a statistically significantly longer calcium flux duration than 800 nM WAY-161503 (Figure ). This indicated light-dose dependent signaling for 5HT2C that could be achieved without deterioration of the response or high global drug concentration. This demonstrates the utility of this tool as a method of performing experiments of long duration and repeatable dosing without the need to exchange cell culture media, an experimentally simple setup and mode of stimulus.