DMNPE-caged D-luciferin (D-Luciferin, 1-(4,5-dimethoxy-2-nitrophenyl)ethyl ester) is a D-luciferin ester derivative which can cross cell membranes efficiently.1,2 Once inside the cells, the ester is continuously hydrolyzed to a supply of D-luciferin. Alternatively a burst of D-luciferin is generated by UV photolysis.