Fig. 2. The IFN- pathway is not constitutively active in melanoma cell lines. Nuclear extracts were isolated from untreated melanoma cells and JKSF cells untreated or treated with 400 units/ml IFN- for 2 h. Extracts were subjected to 10% SDS-PAGE. Immunoblotting was performed using an anti-IRF-1 antibody (Santa Cruz Biotechnology) and ECL. In vitro translated IRF-1 was used as a positive control for IRF-1 detection.