〔Abstract〕 To explore the expression of prohibitin2 (PHB2) in breast cancer and its effect on the bio- logical behaviors of tumor cells . Methods Immunohistochemistry was used to detect the expression of PHB2 pro- tein in breast cancer tissues and its relationship with clinicopathologic features . Breast cancer stable transient cell lines were constructed with knockdown and overexpression of PHB2 , respectively. The effects of PHB2 on cell pro- liferation , 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) pro- tein , Vimentin , and Claudin-1 . The effect of PHB2 on tumorigenicity in vivo was 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 of significantly inhibited the proliferation , migration and invasion ability of breast cancer cells ( P < 0. 01) , while the overexpression of PHB2 significantly 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 knockdown PHB2 mice (P < 0. 000 1) , while PHB2 overexpression 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-cad- herin , Snail and Vimentin decreased significantly after PHB2 knockdown with them in control cells (P < 0. 01) . The expression of Claudin-1 decreased , while the expressions of N-cadherin , Snail and Vimentin increased signifi- cantly in PHB2 overexpression cells (P < 0. 05) . Conclusion PHB2 is highly expressed in breast cancer and pro- motes multiple malignant biological behaviors in tumor cells , suggesting PHB2 may be a potential target for breast cancer diagnosis and treatment.