When the p53 siRNA transfected-SK-Hep-1 cells were treated with OPD (50 μM) for 48 and 72 h, the antiproliferative activity of OPD was decreased compared to that of the control cells (no transfection or scrambled siRNA transfection), suggesting that the anti-proliferative activity of OPD is partly associated with wild-type p53 expression in hepatoma cells (Figure 5B). Here, TP53 is linked to hepatocellular carcinoma.