The importance of bone marrow microenvironment in the pathogenesis of multiple myeloma is becoming increasingly recognized. By using a highly porous three dimensional matrix to provide a substrate for the growth of bone marrow stromal cells, a new mouse model will be developed. This will permit the interaction between multiple myeloma cells and their stromal cells, and will allow for the study of cellular and molecular events regulating in vivo multiple myeloma cell growth and survival.