Fig. 4. p53-mediated apoptosis was enhanced in Cox-2-null cells. Cox-2+/+ or Cox-2–/– MLFs were infected with Ad–GFP, Ad-p53 or Ad-p73α for 24 h. Upper panel: a western blot analysis using lysates prepared from cells infected with Ad-p53 adenoviruses. Lower panels: the patterns of apoptosis analysis by FACScan. The M1 cell population represents apoptotic cells from each sample.