The catenin family of peripheral cytosolic proteins (consisting of three major species) has been determined to bind selectively to the highly conserved cytoplasmic tail domain of the cell-to-cell adhesion cadherin proteins. One of these constituents, beta-catenin, binds directly to the E-cadherin cytoplasmic domain and plays a critical role in intercellular adhesion and signal transduction between neighboring cells. Because beta-catenin has also been determined to form complexes with the tumor suppressor gene product, APC, the protein is also suspected to be important in tumorigenesis. In addition, beta-catenin may be involved in the regulation of gene activity due to its constitutive interaction with transcription factors from the TCF/LEF gene family.

The technique of double immunofluorescence was employed to simultaneously label an adherent culture of rat thoracic aorta (A-10 line) cells (illustrated above) with mouse anti-histone and rabbit anti-beta-catenin primary antibodies, followed by goat anti-mouse and anti-rabbit secondary antibodies conjugated to Marina Blue (histones) and Rhodamine Red-X (beta-catenin), respectively. The culture was counterstained with Alexa Fluor 488 conjugated to phalloidin, targeting the intracellular filamentous actin network. Images were recorded in grayscale with a QImaging Retiga Fast-EXi camera system coupled to an Olympus BX-51 microscope equipped with bandpass emission fluorescence filter optical blocks provided by Omega Optical. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.