Ectopic GATA1 activation induces HSPC apoptosis but prevents programmed cell death of erythroid and megakaryocytic committed cells. (A) PI and annexin V staining of LSK-gated cells from MG-G1ERT2 mouse bone marrow after vehicle treatment (left) or 7 days of tamoxifen treatment (right). (B) Percentages of late apoptotic, early apoptotic, and viable adult bone marrow LSK cells. (C) Flow cytometry analysis of annexin V staining in LT-HSCs, ST-HSCs, MPPs, CMPs, and MEPs from MG-G1ERT2 mouse bone marrow 7 days after vehicle or tamoxifen treatment. (D) Percentages of annexin V+ apoptotic cells based on the data from panel C. Data shown are the means ± SD for three or four mice. *, P < 0.05; **, P < 0.01; ***, P < 0.001 (unpaired Student's t test).