I. To examine the effect of carfilzomib alone or in combination with dexamethasone on the following biologic end points and their correlation with response: measurements of bone remodeling (sodium fluoride F 18 positron emission tomography [PET], serum markers of bone remodeling and the bone marrow osteoblastic and osteoclastic differentiation and function) with the measurement of disease response and proteasome activity in the bone marrow microenvironment.