To investigate whether Cre-mediated deletion of Foxm1 affects the course of leukaemia development in vivo, we injected 100,000 leukaemia cells carrying 4-OHT-inducible Cre or an empty vector control that were pretreated with 4-OHT in vitro for 24 h intrafemorally into sublethally irradiated NOD/SCID mice. The gene discussed is FOXM1; the disease is leukemia.