In this study, inhibition of autophagy by specific downregulation of Atg5 using a lentivirus expressing a targeted shRNA, interrupted breast cancer cell cycle arrest in response to D-arabinose treatment, observed as increased expression of CDK1 and Cyclin B1, as well as reduced levels of p21 and p27 and enhanced cell proliferation potential. This evidence concerns the gene ATG5 and breast carcinoma.