Figure 5. Representative fluorescence microscopic images of actively cycling HCEC from a 73-year-old donor. HCEC were electroporated with control or p21+p16 siRNA and then seeded onto multi-well chamber slides. On Days 1, 5, and 11 after electroporation, cells were immunostained for Ki67 (green) to view actively cycling cells and with DAPI (blue) to visualize all nuclei. Arrowheads indicate Ki67-positive dividing cells. Original magnification was 20×.