Figure 1. Connexin expression in ARPE-19 cells. A: Immunocytochemistry: an antibody to connexin 43 was revealed with Alexa 488-tagged secondary antibody, and the antibody to connexin 46 was visualized by fluorescent microscopy with a cy3-tagged secondary antibody. Punctate labeling characteristic of connexin plaques was seen both in the region of cell apposition (arrows) and at the cell surface. In the left panel, scale bar in the Differential interference contrast (DIC; upper) image represents 40 μm, while scale bar in the phase (lower) image represents 20 μm. B: Western blotting: Aliquot of whole cell ARPE-19 lysate (20 µg total protein) were resolved by SDS–PAGE on a 6% Laemmli gel and transferred to PVDF membrane. Anti-Cx43 antibody labeled several bands corresponding to phosphorylated species of Cx43 (major bands identified by arrows at 69 and 52) and a minor band corresponding to nonphosphorylated Cx43 (arrow at 43). Numbers and lines to the right indicate the positions of molecular weight markers.