CXCR4 and B-cell chronic lymphocytic leukemia: In this regard, patient-associated DNA hypomethylation of the transcription factor NFATC1 (nuclear factor of activated T cells 1), a down-stream effector of the BCR, selectively facilitates expression of CCR7 (but not of other chemokines receptors such as CXCR4) and CCR7-induced migratory responses of CLL cells (76, 83).