Moreover, as genetic mutations/polymorphisms of mtDNA genes might also be a key factor in controlling tumour cell malignancy [50, 51]; a detection of mutations in mt-ND2, mt-ND4, mt-ATP8 and mt-CytB in tested HNC cell lines (Table S6) highlighted great necessity to further define the impacts of these mtDNA mutations during HNC development, in an attempt to find a diagnostic marker for HNCs. Here, MT-ND4 is linked to neoplasm.