In 20 CLL patients exposed to fludarabine-based regimens,23 microarray data analysis of RNA from CD19+-sorted B-cells (GSE15490) showed that UGT2B17 was induced shortly after treatment initiation in 6 of 11 non-responders whereas it was induced in only 2 responders out of 9 (P = 0.0007) (Fig. 1a). Here, CD19 is linked to B-cell chronic lymphocytic leukemia.