Fig. 4. RUNX1 and RUNX2 colocalize in common subnuclear domains. SaOS-2 cells were co-transfected with (A) EGFP-RUNX2 and Xpress (XPR)-RUNX2 (control) and (B) EGFP-RUNX1 and XPR-RUNX2. Whole cell (WC) and nuclear matrix-intermediate filament (NMIF) preparations were performed. The yellow fluorescence in the merged images indicates colocalization between the EGFP- and XPR-tagged RUNX proteins. Cells were stained with 0.05 µg/ml DAPI. Chromatin-extracted NMIF preparations do not present any DAPI staining as expected. Scale bars equal 10 µm.