Yet, our data show that loss of NFAT1 function does not affect leukemia onset and outcome in T-ALL induced in mice by activated NOTCH1 (ICN1) or activated JAK2 (TEL/ETV6-JAK2), indicating lack of tumor suppressive function of Nfat1 in early T cell progenitors. Here, JAK2 is linked to acute lymphoblastic leukemia.