According to a basic working hypothesis, two are the main paths that lead from ALDH1 overexpression to AML progression: (a) the adaptation of malignant cells to oxidized lipids, and (b) the adaptation of AML cells to increased concentrations of retinoic acid due to alterations in their intracellular signaling apparatus (Figure 1). The gene discussed is ALDH1A1; the disease is acute myeloid leukemia.