Afamin secreted from nonresorbing osteoclasts acts as a chemokine for preosteoblasts via the Akt-signaling pathway

► Osteoclasts themselves, not their resorptive activities or precursors, play a central role in osteoclast-osteoblast communication during bone remodeling. ► Osteoclasts in the early differentiation stage secrete potential coupling factors that attract osteoblastic lineages. ► Afamin secreted from differentiated osteoclasts is a possible coupling factor for preosteoblast migration. ► Chemotactic effects of afamin are mediated by Akt-signaling pathway.