FIGURE 4.

Keratins colocalize with SUMO-2/3 during oxidative stress. NIH3T3 cells were transfected with human K8/K18 and were either left untreated (control) or treated with 1 mm H₂O₂ for 45 min prior to immunofluorescence staining. Primary mouse antibody recognizing K18 (DC10) was used to localize K8/K18 heteropolymers, respectively, along with rabbit anti-SUMO-1 or SUMO-2/3 antibodies. Secondary goat anti-mouse Alexa Fluor 488 (green) and goat anti-rabbit Alexa Fluor 594 (red) antibodies were used to visualize the localization of keratins and SUMO by confocal microscopy. K8/SUMO coimmunostaining (not shown) demonstrated analogous results. Shown are representative images from the single channels as well as a merged image with DAPI counterstain showing the cell nuclei. Scale bars, 20 μm.