STAT3 and B-cell chronic lymphocytic leukemia: Confirming the ChIP data, we found that CLL cell nuclear protein extracts from 2 different patients formed complexes with STAT3 binding sites +187 bp – +196 bp, +363 bp – +374 bp, and +382 bp – +391 bp, but not with the putative binding site −93 bp – −83 bp and that the binding was significantly attenuated by the addition of excess unlabeled probe or by anti-STAT3 antibodies (Figure 2C).