Sp1 and c-Jun cooperatively activate the PAI-1 promoter. VSMCs were transfected with PAI-1(-88)/Luc or pAP-1(PMA)-TA-Luc in the presence of pCDNA3.1 empty vector (Con), c-Fos, c-Jun, Sp1, or c-Jun and Sp1. Cells were lysed 1 day after the start of transfection, and luciferase activities were measured and normalized to Renilla luciferase activities of cotransfected pRL-TK. All transfections were performed in triplicate, and results from 3 or more separate experiments are shown in bar graph. ^*Statistical significance with P < .05 by ANOVA.