Bone is a dynamic tissue and requires the precise coordination of formation with loss. Here, Xu Cao and his colleagues show that the bone-chewing activity of osteoclasts results in the local release of active TGF-β1 from the surface of the bone, inducing the migration of nearby bone-forming osteoblastic progenitor cells to this resorbed region. In this manner, proper matching of the localized rates of bone loss and bone creation is ensured (pages 729–731).
