Expression of aurora-A (AURKA), -B (AURKB), and -C (AURKC) as determined by gene expression profiling in memory B-cells (MBCs), polyclonal plasmablastic cells (PPCs), normal bone marrow plasma cells (BMPCs), multiple myeloma cells (MMCs), and human myeloma cell lines (HMCL) within the (A) training and (B) validation group. An asterisk (*) indicates a significant difference between the indexed population and both BMPCs and MBCs at a level of P < .001.