ALDH1A1 and leukemia: What is interesting is that the overexpression of RNA from the gene ALDH1A1 that encodes an aldehyde dehydrogenase that is well suited to protect quiescent stem cells from oxidant stress has a negative prognosis in AML, despite the fact that this gene would be expected to mark leukemia stem cells that do not operate MYC-driven metabolic circuits [82,253,254].