Our findings suggest that in the setting of leukemia, high levels of E-selectin on BMECs bind leukemia cells both along the vascular walls and in the marrow, creating a static environment with minimal turn-over between the blood and bone marrow compartments, thereby inhibiting leukemia cells from exiting circulation, as seen by a lack of clearance of the fluorescent donor CLCs. This evidence concerns the gene SELE and leukemia.