〔Abstract〕 Objective To explore the expression of prohibitin2(PHB2) in breast cancer and its effect on the biological behaviors of tumor cells. Methods Immunohistochemistry was used to detect the expression of PHB2 protein in breast cancer tissues and its relationship with clinicopathologic features. Breast cancer stable transient cell lines were constructed with knockdown and overexpression ofPHB2, respectively. The effects of PHB2 on cell proliferation, migration and invasion ability were detected by clone formation assay, scratch assay and Transwell assay. Western blot(WB) was used to detect the effects of PHB2 on the expression of epithelial-mesenchymal transition(EMT)-related markers, including E-cadherin, N-cadherin, Snail family transcriptional repressor 1(Snail) protein, Vimentin, and Claudin-1. The effect of PHB2 on tumorigenicityin vivowas detected by subcutaneous tumor formation assay in nude mice. Results The result of immunohistochemical showed that PHB2 was highly expressed in breast cancer and the expression of PHB2 was significantly positive correlated with tumor size, human epidermal growth factor receptor-2(HER-2) status and proliferation index Ki-67 levels(P<0.05). Clone formation assay, scratch assay and Transwell assay revealed that knockdown ofPBH2significantly inhibited the proliferation, migration and invasion ability of breast cancer cells(P<0.01), while the overexpression ofPHB2significantly promoted cell proliferation, migration and invasion(P<0.01). The result of subcutaneous tumor formation experiment in nude mice revealed a significant decrease in tumor volume and weight in knockdownPHB2mice(P<0.000 1), whilePHB2overexpression tumors significantly increased in volume and weight(P<0.001).WB assay showed that the protein expression of epithelial marker E-cadherin increased, while the expressions of mesenchymal markers N-cadherin, Snail and Vimentin decreased significantly afterPHB2knockdown with them in control cells(P<0.01). The expression of Claudin-1 decreased, while the expressions of N-cadherin, Snail and Vimentin increased significantly inPHB2overexpression cells(P<0.05). Conclusion PHB2 is highly expressed in breast cancer and promotes multiple malignant biological behaviors in tumor cells, suggesting PHB2 may be a potential target for breast cancer diagnosis and treatment.