PC12-Luc is a cell line derived from the PC12 rat pheochromocytoma cell line that has been genetically modified to express firefly luciferase. Firefly luciferase, as mentioned earlier, is an enzyme that catalyzes a reaction with luciferin to produce light. The PC12-luc cell line is useful in research for studying gene expression, signal transduction pathways, cellular responses to stimuli, drug screening, and other biological processes that involve monitoring changes in gene expression levels in real-time. Researchers use the bioluminescence produced by the luciferase enzyme to measure the activity of specific genes or promoters in these cells.