NOTCH1 and B-cell chronic lymphocytic leukemia: Another important mechanism by which constitutive NOTCH1 signaling promotes CLL cell survival is by sustaining the expression of the antiapoptotic myeloid cell leukemia 1 (MCL-1) protein and the activity of the translational regulator eukaryotic translation initiation factor 4E (eIF4E) (152), which are both implicated in CLL pathogenesis (161, 162).