Multiple myeloma is due to clonal expansion of malignant plasma cells. The incidence in the Nordic countries is approximately 6 new cases per 100,000 per year, which corresponds to nearly 20% of all haematological cancers. Approximately 300 people are gi ven this diagnosis each year in Norway. In most patients the neoplastic clones induce osteoclast activity as well as impaired osteoblast activity, resulting in osteoporosis, osteolytic lesions and pathological fractures that are characteristic for the dis ease. The bone disease of multiple myeloma represents a serious complication that generally is associated with pain and severely reduced quality of life. Multiple myeloma is still an incurable disease, it is likely that new and better treatments of multip le myeloma will emerge from a better understanding of the underlying biology of the disease. WE found Hepatocyte growth factor (HGF) at elevated levels in sera from myeloma patients, and that high serum levels of HGF were associated with apoor prognosis . This project aims, by clinical and pre-clinical studies, to estabish HGF-signaling as a treatment target in multiple myeloma. Furthermore, the project aims at studying the role of Bone Morphogenetic Proteins (BMPs) in multiple myeloma, - in particular t he potential tumor supressor function of BMPs as well as the interplay between BMP - and HGF-signaling in the maintenance of bone homeostasis.