Since the PPARα agonist GW7647 increased PDZK1 expression in Huh-7 hepatoma cells (Tachibana et al., 2008), as well as in Caco-2BBE cells (Figure 8), it is possible that the positive effect of RA on PDZK1 expression exerts its effect via binding of RXRα to the PPRE element as well as the RARE element. Here, RXRA is linked to hepatocellular carcinoma.