This study will investigate aspects related to the role of the bone marrow environment in myeloma. Specifically, the aim is to identify cells in the myeloma microenvironment that stimulate tumor growth and other cell types with opposite effects. Using myeloma-bearing SCID-hu hosts, this lab will test whether various types of novel inhibitors of osteoclasts (bone resorbing cells) can affect tumor growth in these mice. These mice will be treated with infusions of bone forming cells (osteoblasts) to determine if they can affect the course of the disease. Understanding how myeloma cells interact with their environment will help develop effective therapies against multiple myeloma.