AIM: To investigate the role of PPAR ? or ? ligands in regulating the expression of extracellular matrix metalloproteinase inducer(EMMPRIN).METHODS: THP-1 monocytes were induced into macrophages and foam cells in vitro then interfered with clofibrate and pioglitazone.The cells and supernatant were collected after 24 h,respectively.EMMPRIN gene and its protein were assessed by real-time PCR and Western blotting in different interferences.The concentration of matrix metalloproteinases(MMP-9) was measured with ELISA method and the activity of MMP-9 was detected with gelatin zymography.RESULTS: Two known PPAR ? or ? ligands,colfibrate and pioglitzaone,were found,both of which inhibited EMMPRIN expression in macrophages and foam cells.The inhibition was correspondent to the secretion and activity of MMP-9 simultaneously.CONCLUSION: Both PPAR ? and ? ligands inhibit EMMPRIN expression,which may account for their effect on inhibition of MMPs.