Global 2-dimensional hierarchical clustering demonstrates distinct expression signatures for each activating signal. Global 2-dimensional hierarchical clustering was performed on 12 626 genes contained in the U95av2 Affymetrix gene chip using Cluster/Tree View (Eisen Laboratory). The dendrogram (top) shows clustering of ANBL-6. -IL-6 indicates ANBL-6.plxsn in the absence of IL-6; A/MS, ANBL-6.plxsn cells after contact with MM BMSCs; A/S, ANBL-6.plxsn cells after contact with normal BMSCs; N-Ras, ANBL-6 stably transfected with mutant N-ras; IL-6, ANBL-6.plxsn cells stimulated with 10 ng/mL recombinant IL-6.