Fig. 2. A schematic model for S1P-mediated osteoclast precursors localization. The entry of osteoclast precursors from blood vessels where S1P is at high concentration, is initiated by chemorepulsion through S1PR2 (1). Once enter in bone marrow, osteoclast precursors migrate toward chemokines enriched in bone marrow cavity (2). On the other hand, their recirculation toward blood vessels is regulated by chemoattraction through S1PR1 (3).
