Fig. 4

ERK is a negatively feedback regulator for IFN-γ/STAT1 signaling. a. ESCC cell lines EC1 and KYSE150 were treated with U0126 for 3 h, the IFNγ and the receptor mRNA expression was detected by qRT-PCR. b. The active form of IFNγ was detected by ELISA in both cell lines. c. ESCC cell lines EC1 transfected with HA-ca-MEK or empty vector were treated with IFN-γ (10 ng/ml) for 0–60 min. The expression of p-STAT1, STAT1 was measured by Western blot. d. The function study of ERK/STAT1 correlation is detected by colony formation assay. We treated the cells with STAT1 siRNA or scramble RNA and U0126 or control. Similarly, we transfected of STAT1C or empty vector and then treated the cells with constitutive active MEK (HA-MEK) or empty vector together. Then we cultured the cells for 10 days. Similar results were observed in three independent experiments. (*p < 0.05; **p < 0.01) (E.V.: Empty vector)