Prohibitin-1 (PHB) regulates diverse cellular processes by controlling several signaling pathways. In this study, we investigated the functional involvement of PHB in osteoclast differentiation. PHB expression was time-dependently increased by RANKL in BMMs. However, the retroviral over-expression of PHB strongly inhibited the expression of c-Fos and NFATc1, and activation of p38-Elk-1-SRE signaling pathway. Anti-osteoclastogenic action of PHB was significantly inhibited by constitutively active forms of MKK6, but not Elk-1. Collectively, PHB negatively regulates the formation of mature osteoclasts via inhibition of MKK6 activity that affects the activation of the p38-Elk-1 signaling axis required for the expression of c-Fos and NFATcl. (C) 2015 Elsevier Inc. All rights reserved.