Loss of the B-lineage–specific gene expression program in HRS cells.

Examples of molecules affected by this differentiation defect are depicted. Membrane proteins (green), signaling molecules (red), and transcription factors (blue) are either down-regulated or missing (indicated by a black arrow). Up-regulated genes (B7.1 and B7.2) are marked with a gray arrow. Although not identified as consistently down-regulated in the array analysis, Lyn was included in this figure because it is significantly down-regulated in 3 of 4 HL cell lines (the B-cell–derived lines) and also SAGE indicated reduced expression (Table 1).