Use of an antibody as a modulator of osteoprotegerin binding protein (OPGbp) for the preparation of a medicament for preventing or treating bone disease, wherein the antibody or fragment thereof is an antagonist which binds to OPGbp of Figures 4 A-F (SEQ ID NO: 4).Claims 2 to 13 were directed to preferred embodiments of claim 1.II. Two oppositions were filed against the patent on the grounds of A