Bioenergetics profiles of cancer cell lines as a function of oxygen concentration and media composition. (A) MCF7, (B) Huh7, (C) LNCaP, and (D) SaOS2 cell lines were cultured at either 5% O2 or 18% O2 in either DMEM or Plasmax for at least two weeks prior to commencing the assay. Basal, maximal, spare respiratory capacity, proton leak, ATP-linked OCRs (normalized to protein content) were measured using a Seahorse XF96 Flux Analyzer. Data shown are means ± SEM from 3 independent experiments per condition (n = 43 wells per each condition for each cell line). “#” represents differences between 18% O2 and 5% O2 in the same media. “$” represents differences between Plasmax and DMEM when oxygen level is the same. “!” represents differences between 5% O2/Plasmax vs. 18% O2/DMEM. Statistical significance was determined by ANOVA followed by Tukey’s post-hoc analysis.