AML cells maintain a pathological homeostasis between aberrant proliferation and differentiation signals. When chemotherapy is administered, multiple signal pathways are affected. Apoptosis and, as a result, desired clinical response are induced in cases where the above-mentioned balance is impaired in either direction (upper panels). In cases illustrated in the lower panel, both signals are derived from powerful genetic aberrations and balance is maintained despite chemotherapy-induced stress resulting in the survival of the leukemic cells.