TRIM21 and nasopharyngeal carcinoma: Our present study showed that in NPC cells, TRIM21 inhibited mtDNA sensing and type-I IFN responses by suppressing mtDNA release during radiotherapy instead of by directly regulating the STING pathway, which broadens our knowledge of the role of TRIM21 in STING–type-I IFN signalling-mediated antitumour immunity.