Targeting osteoclast-osteoblast communication

The identification of a new mode of cell-cell communication mediated by semaphorin 4D (Sema4D) and Plexin-B1 has added another level to the regulatory balance between bone formation and resorption (pages 1473–1480). This study also highlights Sema4D as a potential target for the development of new therapeutics for osteoporosis and other bone disorders associated with increased resorption.