Oxygen consumption rate (OCR) (a) and extracellular acidification rate (ECAR) (b) of HeLa cells expressing EcSTH and mitoEcSTH before and after addition of 1 μM antimycin A (ANT) measured in pyruvate free HEPES/DMEM+dFBS media. Values are mean ± s.d.; n = 12, 12, 12, 10 for OCR traces in (a), n = 4 for bar graphs depicting OCR quantification in (a), n = 12, 12, 12, 10 for ECAR tracers in (b), n = 4 for bar graphs depicting ECAR quantification in (b) biologically independent samples. The statistical significance indicated for (a-b) represents a One-Way ANOVA followed by uncorrected Fisher’s least significant difference test.