ABT-737 is efficient against a subset of primary myeloma cells. (A) Affymetrix gene expression profiles of purified myeloma cells from 414 newly diagnosed patients, publicly available from the Arkansas Cancer Research Center. The ratio of BCL2 to MCL1 is indicated for each patient in the different molecular groups classified according to Zhan et al⁵  as follows: CCND1-1 (CD-1), CCND1-2 (CD-2), hyperdiploid (HY), low bone disease (LB), MAF (MF), MMSET (MS), and proliferation (PR). (B) Western blot analysis of Bcl-2 and Mcl-1 expression in CD138⁺ purified primary MM cells. A sensitive HMCL (KMS-12-PE) and a resistant HMCL (KMM-1) as well as a CLL sample were included in the panel as controls. Actin was used as a loading control. (C) Analysis of primary myeloma cell sensitivity to ABT-737 (100nM) in function of Bcl-2/Mcl-1 ratio. The Spearman rank correlation coefficient is indicated.