Fig. 4. Photoactivation (PA) of compound 6. (a) Image of live HeLa cells before photoactivation. The magenta outline denotes the region of interest to be irradiated. (b) Image of the same cells as in (a) after irradiation of the region of interest. (c) Quantification of the increase in intracellular fluorescence upon photoactivation of 6; mean and standard deviation are shown along with the values of five independent measurements. (d) Photoactivation reaction of compound 6 to release the fluorophore methylfluorescein. Scale bar = 20 μM.