We assessed the impacts of overexpression and a specific agonist of CB2 on the growth, proliferation, apoptosis, and drug resistance of BC cells in vitro and in vivo using CCK-8, flow cytometry, TUNEL staining, immunofluorescence, tumor xenografts, western blot, and colony formation assays.<h4>Results</h4>CB2 expression was significantly lower in BC compared with paracancerous tissues. Here, CNR2 is linked to breast cancer.