Figure 4
Effects of Δ40p53 on p53 transcriptional activity. (A) Inhibitory effect of Δ40p53 on transcriptional activity of increasing amount of TAp53 in H1299 cells. The transactivation activity of p53 isoforms was measured towards the p53 response element of RGC plasmid and plotted as relative β-galactosidase activity induced by TAp53 expressed alone at 0.5 μg/ml (top panel). TAp53 and Δ40p53 protein expressions were analyzed by immunoblotting using DO-7 and PAb1801 antibodies (bottom panel). The induction of p21WAF1 was also analyzed. Δ40p53 expression increased with the increase of amount of transfected plasmid and TAp53 was constantly expressed. (B) Same reporter assay experiment as defined in (A), but in Saos-2 cells. Each error-bar represents the standard deviation of three independent experiments, each performed in triplicate. Ku80: loading control. *P < 0.05 and **P < 0.01 calculated by t-test. Black arrow: TAp53; white arrow: Δ40p53.