MX1 and leukemia: To determine the functional cooperation between oncogenic mutations in signaling and epigenetic molecules in leukemia, we previously generated mice harboring hematopoietic-selective and pIpC-induced (by Mx1-Cre) activation of oncogenic RAS (NRasG12D) and inactivation of EZH2, the histone H3-Lys27 methyltransferase11 (Fig. 1a).