Effect of BCT on MM-CSCs viability. MM-CSCs were treated with vehicle control or increasing concentrations of BCT for 24 h, and then stained with calcein AM/ethidium homodimer for cell viability/death (A), or annexin V/propidium iodide for apoptosis (B). As described in Materials and Methods, live/dead and apoptotic cells were quantified by flow cytometry (at least 10,000 cells were counted), and the percentage of live, dying, dead, or apoptotic cells was determined using the software provided by the flow cytometer manufacturer. Results represent the means ± SEM of at least 3 independent experiments. Percentage of living (*), dying (x), dead (+), or apoptotic MM-CSCs (*) significantly different from control values as determined by a one-way ANOVA, followed by Bonferroni multiple comparison test (p < 0.05).