Our group described that the pioneer factor KLF4 inhibits homeostatic and antigen-driven proliferation of T cells and that genetic inactivation of KLF4 associates with more aggressive leukemia in NOTCH1-induced T-ALL mouse models and children with T-ALL by aberrantly activating the MAP2K7 signaling pathway [9–12]. Here, MAP2K7 is linked to acute lymphoblastic leukemia.