Figure 3

IFN-gamma upregulates STAT1 expression and stimulates the phosphorylation of STAT1. A, IFN-gamma upregulates STAT1 expression in MDA-MB-468, SUM190, HEKn, and MCF10A cells. The upregulation of STAT1 confirms the presence of the IFN-gamma receptor (48 hours' treatment with 1000 u of IFN-gamma). Endogenous psoriasin expression in MDA-MB-468 is downregulated by IFN-gamma treatment. However, in the SUM190 cell line, endogenous psoriasin expression was not affected by the treatment. Equal amounts of protein lysate for the different cell lines were loaded on the gel. Tubulin assesses equal loading in MDA-MB-468, HEKn and MCF10A cells. GAPDH assesses equal loading in SUM190 cells. B, Treatment with 1000 u of IFN-gamma led to the phosphorylation of STAT1 five and 15 minutes after IFN-gamma treatment in MDA-MB-468 cells, which confirms an active signaling pathway. Reduced phosphorylation of STAT1 was observed in the SUM190 cell line. 100 μg of protein lysate were loaded on the gel. GAPDH assesses equal loading. C control.