Abstract: Objective To construct the eukaryotic expression plasmid BFP-cyclin D1 and investigate the effects of cyclin D1 on the proliferation and migration of MCF-7 cells. Methods The cyclin D1 gene was amplified by RT-PCR from total RNA of MCF-7 cells， digested with EcoR I and Sal I， and inserted into the eukaryotic florescence expression vector pEBFP-N1.The resulting recombinant plasmid BFP-cyclin D1 was transfected into MCF-7 cells.In parallel，one negative control group was transfected with pEBFP-N1 and another with transfection reagent without any DNA.Following transfection，cell proliferation was detected by MTT assay，cell migration by cell scratch assay，and mRNA expression by quantitative real-time PCR. Results The eukaryotic expression plasmid BFP-cyclin D1 was successfully constructed and high expression of cyclin D1 was detected in MCF-7 cells.Cell proliferation and migration were significantly higher in the cells transfected with BFP-cyclin D1 than in the two control groups（P<0.01）. Conclusions High expression of cyclin D1 can accelerate proliferation and migration of MCF-7 cells，perhaps by shortening the cell cycle and promoting DNA replication.

Key words: Breast cancer, Cyclin D1, MCF-7, MTT, Cell proliferation and migration