[Molecules which are involved in osteoclastic bone resorption: from the aspect of targets of treatment for osteoporosis].

: Bone in vertebrates is continuously destroyed and reformed to maintain bone volume throughout their life. In normal bone remodeling, osteoblastic bone formation follows osteoclastic bone resorption in a precise and quantitative manner. In osteoporosis, the bone resorption surpasses the bone formation. Recent studies have shown that osteoclastic bone resorption is tightly regulated by bone-forming osteoblasts. Osteoblasts express RANKL (receptor activator of nuclear factor-KappaB ligand), which plays central roles in osteoclast differentiation and function. In this review article, we explain molecules which are involved in the RANKL-RANK interaction in the regulation of osteoclastic bone resorption.