The adherent culture of opossum kidney cortex proximal tubule epithelial cells (OK line) featured in the image above was transfected with a EYFP-actin subcellular localization vector, thus localizing a green-yellow fluorescent protein tag to the filamentous actin cytoskeletal network. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon TE-2000 inverted microscope equipped with a bandpass emission fluorescence filter optical block. During the processing stage, the EYFP channel was pseudocolored green. A separate channel was recorded using differential interference contrast and overlaid on the fluorescence channel to identify cell boundaries and common structural features, such as the nucleus.