Figure 4

IFN-α dependent activation of Tyk2 and Jak1 is prevented in resistant Huh-7 cells. Cured S-5/15 and R-17/3 cells were treated with IFN-α 2 b (1000 IU/ml) or IFN-γ (1000 IU/ml) for different time intervals 10, 30 and 60 minutes and cell lysates were examined for Jak1 and Tyk2 phosphorylation by Western blot analysis. Left panel shows the time dependent phosphorylation of Jak1 and Tyk2 kinases in sensitive Huh-7 cells (S-5/15) by IFN-α and IFN- γ (1000 IU/ml). Right panel shows the phosphorylation of Jak1 and not Tyk2 in resistant Huh-7 cells (R-17/3) by IFN-α and IFN-γ (1000 IU/ml). β-actin levels are the same among the protein samples analyzed.