Fig. 1. Endogenous Runx2 is associated with the nuclear matrix in osteoblastic cells. ROS 17/2.8 cells grown on gelatin-coated coverslips were processed for whole cell (WC) or nuclear matrix-intermediate filament (NM-IF) preparations and in situ immunofluorescence as described in Materials and Methods. Rabbit polyclonal antibody against Runx2 was used at a dilution of 1:200 (Javed et al., 2001). Secondary antibody used was Alexa 468 (goat against mouse) at a dilution of 1:800. The middle panel shows 4',6-diamidino-2-phenylindole (DAPI) staining, which is absent in NM-IF preparation as chromatin has been removed. Right panel shows phase contrast image of the same cell.