DMNPE-caged luciferin can be used to measure intracellular functions since it readily crosses cell membranes. Once it is inside the cell, active luciferin can be released by UV light or by the action of endogenous intracellular esterases. DMNPE-caged luciferin makes it easier to follow the changes in gene expression in live cells. It can also be used in combination with DMNPE-caged ATP.