In order to determine whether Klf5 deficiency impairs B-cell leukemogenesis once leukemia have been initiated, we generated Mx1-Cre;Klf5flox/flox mice where the deficiency of Klf5 can be induced after transplantation [31] in recipient mice where leukemogenesis has already been initiated [34]. Here, MX1 is linked to leukemia.