Considering the role of p53 as a transcriptional activator of Siah-1 expression [40] and the potential of HBx and ATRA to upregulate p53 levels (Figure 1, Figure 2, Figure 3 and Figure 4), it can be assumed that ATRA and HBx, individually or in combination, activate Siah-1 expression via upregulation of p53 levels in human hepatoma cells. This evidence concerns the gene TP53 and hepatocellular carcinoma.