The adherent culture of normal Syrian golden hamster kidney fibroblast cells (BHK-21 line) featured in the image above was transfected with a mixture of DsRed2 FP-endoplasmic reticulum and EGFP-nucleus subcellular localization vectors, thus localizing a green fluorescent protein tag to the nucleus and an orange-red probe to the endoplasmic reticulum. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon TE-2000 inverted microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, the enhanced green fluorescent protein channel was pseudocolored green while the DsRed2 FP channel was pseudocolored red. A separate channel was recorded using differential interference contrast and overlaid on the fluorescence channels to identify cell boundaries and common structural features, such as the nucleus.