Mitochondrial respiration: Representative mitochondrial respiration in parental (a) and resistant (b) KTCTL-26 cells after 24 h treatment with 20 µM ART (=treated). Untreated cells served as controls. Data pertaining to the oxygen consumption rate (OCR) were normalized to total basal respiration (set to 100%) consisting of mitochondrial and non-mitochondrial respiration. Extracted values for mitochondrial basal oxygen consumption rate (OCR) (c), maximal OCR (d), respiratory reserve capacity (e), and adenosine triphosphate (ATP) production (f) after 24 h ART application (ART). MFI = mean fluorescence intensity. Error bars indicate standard deviation (SD). Significant difference to untreated control: * p ≤ 0.05, ** p ≤ 0.01, ns = not significant. n = 4.