gene expression profiles of purified plasma cells (PCs) obtained from a plasma-cell leukemia patient (MM). PCs were purified from bone marrow samples, after red blood cell lysis with 0.86% ammonium chloride, using CD138 immunomagnetic microbeads. The purity of the positively selected PCs (93%) was assessed by morphology and flow cytometry. 5 micrograms of total RNA was processed and hybridized to the Affymetrix HG-U133A chip following the manufacturer's instructions. After scanning, the image was processed using Affymetrix MicroArray Suite (MAS) 5.0 software to generate gene expression intensity values. Arrays normalization was performed normalizing the signals to the target intensity of TGT=100. Keywords = Gene expression profiling Keywords = IGH translocations Keywords = MGUS Keywords = Multiple Myeloma Keywords = Plasma Cell Leukemia