MFN2 and neoplasm: Parkin was reported to be ubiquitinated by K6 linkage and the modification hinders the process of mitophagy.43 Another study identified Mitofusin-2 as a substrate of K6 linkage using a K6-specific affirmer.44 The tumor suppressor gene, BRCA1, is known to be responsible for assembling K6 linkage through its E3 ubiquitin ligase activity,45 suggesting that K6 linkage may be essential in BRCA1-mediated tumor suppression.