Inhibition of MMP-1 expression is mediated by IFNγ-induced ATF-3. A, THP-1 cells transduced with control DSRed2-shRNA- or STAT1-shRNA-encoding lentiviral particles were stimulated with LPS (3 hr) with or without IFNγ pre-treatment. B, Nuclear extracts from LPS-stimulated primary monocytes (with or without IFNγ pre-treatment) were subjected to EMSA with a radiolabeled CRE oligonucleotide probe. C, Nuclear extract samples were preincubated for 60 minutes at 4°C with control or ATF-3-specific antibodies as previously described (51) and analyzed by EMSA. D, Primary monocytes were stimulated with LPS (3 hr) with or without IFNγ pre-treatment. Chromatin was immunoprecipitated using control (IgG) or ATF-3 antibodies and analyzed by PCR. E and F, THP-1 cells transduced with control DSRed2-shRNA- or two different (labeled #1 and #2) ATF3-shRNA-encoding lentiviral particles were stimulated with LPS (3 hr) with or without IFNγ pre-treatment and mRNA levels were analyzed using real time PCR.