MYC and B-cell chronic lymphocytic leukemia: On the other hand, CLL cells from Eμ-TCL1 mice showed varying levels of c-MYC expression, with some mice expressing it at a similar level as B cells from Eμ-Myc mice (Fig. 5c), which harbor a B-cell-specific transgenic expression of Myc via the IGVH promoter and Eμ enhancer and develop a very aggressive lymphoma [28, 29].