Mild hypoxia activates HIF-1α and HIF-2α, and up-regulates miR-146a expression without significant decrease of CXCR4 protein levels, in primary M5-AML. (A) Western blot analysis shows that HIF-1α and HIF-2α are activated in leukemic blast cells maintained 20 h under mild hypoxia (Hx), as compared to normoxia (N); Nucleolin is an internal control of nuclear proteins extracts. (B) Quantitative reverse transcriptase polymerase chain reaction shows that miR-146a is significantly up-regulated (mean ± SEM values are, in N: 2.6±0.4; in Hx: 8.9±2.8; and P=0.0424) in leukemic blast cells, obtained from eight patients with AML-M5, maintained in Hx, as compared to N. (C) Flow cytometry analysis of CXCR4 membrane protein level observed on leukemic blast cells in Hx (mean ± SEM values are, in N: 21.9±6.0; in Hx: 15.8±4.9; and P=0.4417), as compared to N. (A–C) One representative experiment out of three is shown.