STUB1 and osteosarcoma: These findings may be pathologically relevant, because type I and II IFN, which play crucial roles in osteosarcoma, can induce transcription of NDP52.[14] In addition, STUB1 may be a target of covalent ISG15 conjugation, which is similar to ubiquitination and increases STUB1 E3 activity, and ISG15 is highly inducible by type I IFNs.[23]