Western blot analysis of the Jak-Stat signaling pathway in IFN-sensitive and IFN-resistant cell lines. Three representative cured Huh-7 clones of IFN-resistant and one Huh-7 clone of IFN-sensitive cell line were treated with IFN-alpha (1000 IU/ml) for 30 minutes. Cell lysates were prepared and then equal amounts of protein lysates were used to examine the expression of IFN-receptor (IFNAR1), Jak-1, Tyk2, Stat 1, Stat 3 and Stat 3, phosphorylated Stat 1 and Stat 2 by Western blot analysis. Beta actin levels were used, as a control to make sure that equal amount of protein was present in the extracts. All IFN-resistant cell lines have reduced expression of Tyk2 and showed lack of Stat phosphorylation.