HG U133 Plus 2.0 Affymetrix microarrays were used to determinate the expression level of 11 genes involved in the extrinsic apoptosis pathway. Histograms show the mean gene signal intensity in 6 memory B cells (MBC), 7 polyclonal plasmablasts (PPC), 7 bone marrow plasma cells (BMPC) obtained from healthy donors, 92 purified myeloma cells (MMC), 7 BM stromal cells (MSC), 7 in vitro-generated osteoclasts (OST) and 5 CD3+, CD14+ and CD15+ cells from newly diagnosed myeloma patients.