Fluorescence emission intensity from a culture of rat kangaroo kidney epithelial cells (PtK2 line) that were immunofluorescently labeled with primary anti-cytokeratin (an intermediate filament protein) mouse monoclonal antibodies followed by goat anti-mouse Fab fragments conjugated to Marina Blue. The ultraviolet absorption maximum of Marina Blue is 365 nanometers and the emission maximum occurs at 460 nanometers. In addition, the specimen was simultaneously stained for mitochondria with MitoTracker Red CMXRos. Note the absence of signal from the red fluorophore with this bandpass emission filter combination.