In the context of cancer progression, it was shown that ubiquinol–cytochromec reductase core protein II (UQCR2), an important subunit of complex III, is upregulated in human tumours, including lung adenocarcinoma and breast cancer.45 Interestingly, UQCR2 negatively regulates p53 levels by inducing its degradation through the interaction with PHB, a p53 chaperone. This evidence concerns the gene TP53 and breast cancer.