STAT1 and hepatocellular carcinoma: Therefore, we had to prestimulate hepatoma cells with exogenous human IFN-β (1,000 U/ml) for 24 hours, which then led to a significant induction of expression of both IFIT-1 and STAT1 and its phosphorylation (P-STAT1) in all three hepatoma cell lines (Figure 7; lane 2 in all panels).