SPP1 and hepatocellular carcinoma: To define the specific changes associated with metastatic progression, we analyzed an additional 10 pairs of HCC samples with quantitative real-time polymerase chain reaction (qRT-PCR) analysis, and found that OPN levels were low in nontumorous tissue, relatively higher in primary HCCs by 4.5-fold and further increased in PVTT by 11.7-fold (Supplementary Figure 11D).