Development of compound transgenic models, in which the expression of mutant IDH2 was combined with Meis1 and HoxA9, led to the development of leukemic cells that were dependent on the expression/function of mutant IDH for their growth/survival; on the other hand, compound transgenic IDH2-R140Q; Flt mice showed that mutant IDH cooperates with FLT3-ITD in leukemia inhibition in vivo [104]. The gene discussed is MEIS1; the disease is leukemia.