First hints that 5‐LO might be involved in the regulation of myeloid cell differentiation and stem cell maintenance came from the observation that 5‐LO is required for the aberrant self‐renewal capacity of leukemic stem cells in a BCR/ABL chronic myeloid leukemia model (CML), knockout of 5‐LO prevented CML development in the mice.16 This evidence concerns the gene ALOX5 and chronic myelogenous leukemia, BCR-ABL1 positive.