Vinculin is a protein 117 kiloDaltons in size that is associated with focal adhesion and adherens junctions, which are complexes that serve as nucleation sites for actin filaments and as crosslinkers between the external medium, plasma membrane, and actin cytoskeleton. The head region of vinculin contains the binding sites for the proteins talin and alpha-actinin, and its tail region, which is rod-like in shape, contains the binding sites for filamentous actin and paxillin. Investigations indicate that a proline-rich domain between the head and tail of vinculin interacts with vasodilator-stimulated phosphoprotein (VASP), a substrate of cyclic AMP-dependent or cyclic GMP-dependent kinases. Recent studies of vinculin suggest that the role the protein plays in cellular adhesion, motility, and intercellular communication varies depending upon alterations in the three-dimensional structure of the protein. For example, it has been demonstrated that by alternating between an active and inactive form, vinculin can regulate the mobility of cells, and may, therefore, be involved in wound healing, embryonic tissue development, and the metastasis of cancerous tumors.

The adherent culture of APM cells featured above was immunofluorescently labeled with anti-vinculin mouse monoclonal primary antibodies followed by goat anti-mouse IgG secondary antibodies conjugated to Texas Red. In addition, the specimen was simultaneously stained for DNA with the ultraviolet-absorbing probe Hoechst 33258, and for the cytoskeletal filamentous actin network with Alexa Fluor 488 conjugated to phalloidin. 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.