RBBP5 and plasma cell myeloma: However, Liu et al. [19] reported that downregulation of RBBP5 reduced sensitivity to bortezomib and mitoxantrone in RPMI 8226 and NCI-H929 myeloma cell lines adherent to bone marrow stromal cells, indicated that RBBP5 might be the target of bortezomib and mitoxantrone.