Much attention has focused on osteoblast and osteoclast biology, but little research has been performed on the cell that composes 90% of all bone cells--the osteocyte. Osteocyte function has been difficult to study because these cells are embedded in mineralized tissue and are difficult to obtain in reasonable numbers and purity. Establishment of an osteocyte cell line makes it possible to study osteocyte function more readily and easily by the application of protein chemistry and molecular biology. We have established a cell line that appears to have the properties of primary osteocytes.