Pre-leukemic gain of self-renewal in immature T-cells was recently uncovered as an initiating event in T-cell acute lymphoblastic leukemia, T-ALL. We will investigate the roles of TET2, an enzyme that catalyzes DNA demethylation, in regulating this pre-leukemic self-renewal and evaluate the potential of using demethylating agents as a therapeutic strategy for the treatment of this aggressive leukemia.