Therefore, an attempt was made to identify the possible in vitro anti-cancer molecular mechanisms studied on breast cancer (BC) cell lines.<h4>Methods</h4>An advanced literature search was conducted in the PubMed database using search terms "Metformin, Cell culture, Breast neoplasms." Different anti-cancer molecular mechanisms induced by metformin (MET) identified in cell culture studies are presented in this paper.<h4>Results</h4>It was identified that MET induces molecular pathways that exert anti-cancer effects when treated on BC cells. Here, MET is linked to cancer.