As shown in Figure 1A-D, endogenous or Flag-tagged MTUS1/ATIP1 was colocalized with mitochondria and also colocalized with the mitochondrial marker COX IV and the mitochondrial outer membrane (MOM) proteins MFN1/2 and TOMM20 in HNSCC cells. This evidence concerns the gene COX4I1 and head and neck squamous cell carcinoma.