The balance of degradation and bone formation is important for the normal process of remodeling and maintenance of bone mass. Genetic, hormonal, immunological and other factors affect bone remodeling throughout life. Disorder of bone turnover plays key role in the pathophysiology of osteoporosis and presents a complex process which involves bone cells, cytokines and their receptors. Nowadays, important role of RANK/RANKL/OPG system in the pathophysiology of osteoporosis is well known, but it is still important to investigate the intracellular signaling pathways in the development of osteoporosis and other metabolic bone diseases.