This research project will focus on the role of acquired drug resistance during chemotherapy and the various biological mechanisms that may be involved in this important clinical development. Various mechanisms of cellular resistance to chemotherapy have been described, but these do not seem to have a decisive role in the clinical response. Therefore a new, putative role in drug resistance of an intracellular organelle, the vault complex, that is strongly expressed in certain myeloma patients, will be investigated. The questions of why vaults are so abundantly present in myeloma cells (much less in other cancer cells) and what their function is will be addressed. The investigators will use modern genetic techniques to identify the meaning of vaults for myeloma treatment.