The present invention relates to a method of producing osteocyte cell line in various stages of differentiation. Such cell line remains stable after more than 20 passages. The osteocyte has a stellate shape with dendritic processes and expresses high level of osteocalcin. More specifically, it provides a method of production for cultured osteocytes of various differentiation stages. Furthermore, it relates to osteocyte cell line, and more specifically cultured osteocyte. The invention also relates to a method for the production of monoclonal antibodies using such cultured osteocytes and further relates to hybridomas and monoclonal antibodies which recognize an osteocyte-specific antigen. Finally, the invention relates to a method of screening for modification factors and binding factors for osteocytes.