TP53 and colon carcinoma: In addition, based on our results, we can exclude a selective downregulation of cytochrome c oxidase (complex IV) in HNSCC tumors carrying an inactivating p53 mutation, which was postulated based on results from cultured colon carcinoma cells [15], since nuclear enrichment of this major tumor suppressor was found in samples with high COX1 levels (Supplementary Figure S3A).