All Phf6fl/y,RE9a (WT Phf6,RE9a) mice rapidly succumbed to leukemia characterized by significantly increased white cell counts and decreased PLT counts in PB as compared to Vav1-Cre;Phf6fl/y,RE9a (VC Phf6,RE9a) mice in passage 3 (Fig. 2A). Here, VAV1 is linked to leukemia.