Meis1 regulates oxidative stress. (A) Representative flow cytometry plot showing results of dichlorofluorescein diacetate staining (a measurement of ROS levels) gated on LT-HSCs. (B) Bar graph depicting results of colony-formation assay performed with Meis1-flox/CreER lineage-depleted cells that were treated in vitro with vehicle (ethanol) or 4-OHT in the presence of the ROS scavenger N-acetyl cysteine (NAC), 1 of 2 shRNA constructs directed against VHL (shVHL1 and shVHL2), scrambled shRNA, or cobalt chloride (treatment conditions labeled on the bottom of the graph). Colony numbers (vertical axis) were normalized to those formed by vehicle-treated cells in each experiment. Data represent means ± SEM of triplicate colonies from 1 representative experiment. (C) Lineage-negative BM cells of Meis1-flox/CreER and control mice were treated with 4-OHT for 48 hours and then analyzed by whole genome microarrays. Depicted are gene-set enrichment analysis plots of the analysis showing enrichment in the control cells compared with Meis1-deleted of gene sets associated with leukemias that express high levels of Meis1 (top panel) and those associated with hypoxia-response (bottom panel). The gene sets are labeled on the top of each plot. (D) Western blot (top panel) showing levels of Hif-1α and actin (loading control) in whole BM of control (first 2 lanes) and Meis1-deleted mice. Bottom panel depicts Western blot results of Hif-1α and actin in vehicle- or 4-OHT–treated cells transduced with lentivirus expressing shRNA against VHL or a nontargeting construct.