FIGURE 2.

TRAF2 regulates AP-1 activity. A, overexpression of TRAF2 increases AP-1 activity. Various amounts of FLAG-TRAF2-WT or FLAG-TRAF2-DN were transfected with a plasmid mixture containing the AP-1-luciferase reporter gene (100 ng) and the Renilla luciferase gene (20 ng) for normalization. At 24 h after transfection, the firefly luciferase activity was determined in cell lysates and normalized against Renilla luciferase activity. Significant differences were evaluated using Student's t test, and the respective asterisks indicate a significant difference (p < 0.05). B, AP-1 activity is decreased in TRAF2 knock-out MEFs. TRAF2 knock-out MEFs were co-transfected with a plasmid mixture containing the AP-1 luciferase reporter gene (0.4 μg) and the Renilla luciferase gene (0.1 μg) for normalization. At 20 h after transfection, cells were starved for 16 h and then treated with EGF (20 ng/ml) for various times as indicated. Firefly luciferase activity was determined in cell lysates and normalized against Renilla luciferase activity. Significant differences were evaluated using Student's t test, and the respective asterisks indicate a significant difference (p < 0.05). C, AP-1 activity is decreased in TRAF2 knockdown HaCaT cells. TRAF2 knockdown cells were co-transfected with a plasmid mixture containing the AP-1 luciferase reporter gene (0.8 μg) and the Renilla luciferase gene (0.2 μg) for normalization. At 20 h after transfection, cells were starved for 16 h and then treated with EGF (20 ng/ml) for various times as indicated. Firefly luciferase activity was determined in cell lysates and normalized against Renilla luciferase activity. Significant differences were evaluated using Student's t test, and the respective asterisks indicate a significant difference (p < 0.05).