BCR and B-cell chronic lymphocytic leukemia: However we do know that in CLL, activation of NF-κB after CD40-CD154 ligation, or activation of NFATC1 transcription factor, the downstream effector of BCR, results in both expression of CCR7 and Bcl2, therefore both events seem related to one shared former event (67, 76, 104, 105).