Vitamin K2 (VK2, menaquinone) is a drug for osteoporosis. VK2 acts as a cofactor for γ-glutamyl carboxylase, which catalyzes the carboxylation of specific glutamic acid residues (γ-carboxylation) of substrate proteins. Here we demonstrate that VK2 also regulate osteoblastgenic marker gene expression. Using VK2-immobilzed nanobeads new target proteins were purified and identified from osteoblastic cell line. They are prohibitin 1 and 2 (PHB1 & 2), respectively. To confirm the PHBs function on VK2-dependent transcription, PHB1 & 2 were knock-down and osteocalcin gene 2 transcriptions were analyzed, indicating that PHBs regulate VK2-dependent transcription. Taken together PHBs are VK2 target proteins for osteoblastgenic transcription.