MRC5/RFP-luciferase cells are derived from he human fibroblast cell line MRC5 by stably integration of a constitutive RFP-firefly luciferase expression construct. MRC5 cells are widely used in the studies of cell biology, virus biology, cellular aging and toxicology. MRC5/RFP-Luciferase cells stably express both RFP and firefly luciferase reporters, can be used for in vitro assays and in vivo imaging.