Macrophage activation affects cytoskeleton. Differences in morphology of differently activated macrophages visualised by actin organization (red) Cdc42 distribution (green) and a nuclear stain Hoechst (blue). (A) The M1 macrophages have the actin concentrated at the cell cortex and the Cdc42 is randomly distributed throughout the cell. M1 macrophages are more elongated than the M2, the actin in M2 is more diffusely distributed throughout the cell compared to M1, and Cdc42 is restricted to the nucleus. Control macrophages have a morphology in between these polar ends and the Cdc42 is present in the nucleus as well as in the cytosol (B). After stimulation with CCL2 for 10 minutes the cytoskeleton rapidly changes, and all activated macrophages adopt a spherical appearance. In M1 macrophages the Cdc42 distribution remains in the cytosol, the M0 macrophages have the Cdc42 co-localizing with actin in the cytosol. M0 and M2 macrophages develop filopodia and the Cdc42 co-localizes with the actin (B).