Effect of AP-1 protein overexpression on basal and D dimer-inducible PAI-1 transcriptional activating activity. Subconfluent rat lung fibroblasts were cotransfected with plasmids expressing either wild-type c-fos (c-fos) or JunD (JunD), a nonfunctional mutant c-fos (DNA-binding basic region deleted; fos BR), or a peptide containing an acidic amino acid-substituted DNA binding region (A-fos) along with the indicated PAI-1 promoter-luciferase reporter constructs and the transfection control Renillaluciferase reporter plasmid. p161con, p161wt, p161mut, and p48 PAI-1 promoter-luciferase constructs are as defined in Fig 1. Results are plotted as the ratio of firefly/Renilla luciferase activities (mean + SE) relative to the activity ratio seen with the empty vector. (A) Sequence specificity of c-fos induction. (▨) Empty vector; (□) fos BR vector; (▪) c-fos vector. *P < .05 relative to the mutant fos values. (B) Effect of dominant negative c-fos (A-fos) on D dimer inducibility of p161wt. Fibroblasts were transfected as described above and exposed to 0.4% serum-containing media for 48 hours followed by either D dimer (1 μmol/L) or serum-free media for 6 hours. (▨) Empty vector; (□) A-fos vector; (▪) JunD or JunD/c-fos vectors. *P < .05 relative to the empty vector. +P < .05 relative to the c-fos vector by ANOVA/Newman-Keuls test.