Although HIF proteins are mainly activated by hypoxia, several reports indicated that expression and/or activity of HIF‐1α/HIF‐2α are also regulated by STAT3 (Signal Transducer and Activator of Transcription 3) and STAT5 in normal and cancer cell types including CML LSCs.19, 20, 21. Here, STAT5B is linked to chronic myelogenous leukemia, BCR-ABL1 positive.