To study the role of all-trans retinoic acid(ATRA) in cell cycle, proliferation, differentiation and apoptosis of breast cancer cell line MCF-7 and the expression of restin gene. Methods: The cell cycle was observed by means of flow cytometry(FCM) , the cell proliferation was detected by MTT assay and the expression of restin mRNA was examined by RT-PCR. Results: Under the treatment by ATRA, the cell growth arrested at G1 phase and the proliferation was inhibited greatly. The level of restin mRNA was found to be up-regulated by ATRA in MCF-7 cell. Conclusion: G1 phase arrest and proliferation inhibition were involved in the process that ATRA induces MCF-7 cell differentiation and apoptosis, and restin maybe play an important role in this process, especially the cell apoptosis.