FLT3 and acute lymphoblastic leukemia: Inactivation of Ezh2 alone resulted in increased numbers of DN3 cells (CD4–/CD8–/CD44–/CD25+).87 Interestingly, addition of a Ras signalling pathway mutation (FLT3–ITD) to Ezh2–Runx1 dual knockout mice resulted in the development of a highly aggressive ALL, with an increase in the number of immature T cells.