As in the MD4+/−/Eμ-TCL1 mice, B cells were able to recognize HEL, but CLL cells in older AID−/−/MD4+/−/Eμ-TCL1 mice failed to bind to HEL, indicating that AID was not causing the loss of HEL recognition (Fig. S1A). Here, AICDA is linked to B-cell chronic lymphocytic leukemia.