Available data indicate that protonmotive force (Δp), NADH/NAD ratio, CoQH2 (reduced coenzyme Q)/coenzyme Q ratio, and local O2 concentration determine the rate of ROS production.15,20 In addition, recent findings reveal that complex I subunit NDUFB3 (NADH:ubiquinone oxidoreductase subunit B3) regulates ROS production,21 and NDUFB3 downregulation is associated with thyroid cancer progression.22 Here, NDUFB3 is linked to thyroid gland carcinoma.