MCL1 and B-cell chronic lymphocytic leukemia: Additional work has directly compared CD38+ to CD38- CLL clones and found that CD38+ cells have an enhanced migratory ability in response to the chemokine CXCL12 [58], thus enhancing their homing to lymphoid tissue, as well as higher levels of VEGF and Mcl-1 [59], indicating CD38+ CLL cells have a heightened survival advantage within the microenvironment compared to CD38- clones.