Fig. 7

Ouabain induces caspase-dependent apoptosis in AML cells. AML KG-1 cells were treated with ouabain (30 nM) in the presence or absence of caspase 8 inhibitor zVAD-IETD (10 μM) and caspase-9 inhibitor zVAD-LEHD (10 μM) for 48 h. A Percentage of apoptosis as evaluated by Annexin V/7-AAD assay. B Representative micrographs of Hoechst 33342 nuclear staining under an inverted fluorescence microscope. Condensed and/or fragmented nuclei were considered apoptotic cells. Scale bar = 100 μm. C Western blot analysis of pro- and cleaved (active) caspase-3 (C3), caspase-8 (C8), and caspase-9 (C9) levels upon ouabain treatment (0 − 40 nM) for 24 − 72 h. β-actin was used as a loading control. Quantitative analysis of caspase activation as a ratio of cleaved to pro-C8 and C9 levels by densitometry is shown (see also Additional file 1: Fig. S6). Data are mean ± SD (n = 3). ^*P < 0.05, ^**P < 0.01, ^***P < 0.001 versus nontreated control cells; two-sided Student's t test