Figure 15. Long-term treatment with DPI is surprisingly “non-toxic”. To determine the long-term effects of DPI (10, 25 and 50 nM), MCF7 cells were cultured for an entire month, in the presence of the drug. Then, their mitochondrial respiration was assessed by metabolic flux analysis. Panel (A) shows that all three drug concentrations show near complete inhibition of mitochondrial respiration. Panel (B) illustrates the morphology of cells after 4 weeks of DPI treatment. Note that the morphology and density of the cells is relatively unchanged, especially at a DPI concentration of 10 nM. Media with DPI or vehicle alone was replaced every 2 to 3 days, during the period of 1 month. Cells undergoing long-term treatment with DPI were also successfully passaged, after harvesting by standard trypsinization techniques.