PML and hepatocellular carcinoma: However, we found that strong expression of SIAH-1/2 in human HBV-related HCC specimens did not correlate with downregulation of PML (Figure 1), suggesting that PML is not a physiological substrate of SIAH-1/2 and the supposed negative interaction between PML and SIAH-1/2 may not account for the tumorigenic effect of HBsAg.