Fig. 5. Increasing the concentration of calcium ions in the medium induces co-localization of BP180, actinin-4 and actinin-1 at cell-cell contact sites in pp126 oral keratinocytes. pp126 oral keratinocytes were ‘switched’ to medium containing 2.0 mM calcium for 4 hours and then were processed for double-label indirect immunofluorescence microscopy using a combination of antibodies against actinin-4 and BP180 (A,B) or actinin-1 and BP180 (D,E). Both actinins and BP180 co-distribute at cell-cell contact sites (arrows in A-E). The overlapping staining patterns appear yellow in the overlays (C,F). Bar, 10 µm.