Multi-color BiFC experiments using onion epidermal cells. Onion cells were transfected by particle bombardment and visualized using laser scanning confocal microscopy. Labels above each set of panels indicate the various constructions introduced into the cells. Labels below each set of panels indicates the filter set/channel imaged. mCherry-VirD2NLS labels the nucleus. Note that, regardless of the tag, Impa-1 localizes to the cytoplasm and Impa-4 localizes predominantly to the nucleus, with some cytoplasmic staining. In Panel A, the arrows indicate a gold particle in the nucleus. Imaging of gold particles results from 458 nm and 488 nm laser reflection. Because Cerulean images weakly using the Zeiss LSM510 Meta confocal microscope, the Cerulean images in Panels A and B were digitally enhanced by adjusting the brightness and contrast, in accordance with . DIC, differential interference contrast image.