Abstract: Objective: To clone the activating transcription factor-2(ATF-2) gene,then construct the recombinant eukaryotic expression vector with ATF-2,and explore the effects of ATF-2 on the gene expression of matrix metalloproteinase-20(MMP-20) in mice ameloblasts.Methods: The reverse transcription PCR primers of ATF-2 were designed.The total RNA from the mice ameloblasts was extracted to obtain cDNA for PCR amplification.The ATF-2 gene containing Hind Ⅲ and xhol restriction sites was inserted into the eukaryotic expression vector(pcDNA 3.1/myc-HisA).The effects of ATF-2 on the transcriptional activity of MMP-20 was observed after transfecting the recombinant plasmid.Results: One thousand four hundred and sixty-three bp gene fragment was amplified through PCR.The recombinant eukaryotic expression vector with ATF-2(pcDNA 3.1/myc-HisA-ATF-2) was successful constructed by the verification of dual enzyme digestion and sequencing.The luciferase test showed that ATF-2 gene could promote the expression of MMP-20 promoter(P<0.01).Conclusions: The recombinant pcDNA 3.1/myc-HisA-ATF-2 expression vector is successful constructed.ATF-2 can positive regulate the promoter activity of MMP-20.