AMFR and neoplasm: Previously, Gp78 knockdown in the HT-1080 cells studied here did not affect tumor growth but did inhibit metastasis [41]; further, impaired metastasis was rescued by wild-type Gp78 but not a RING finger Gp78 mutant with deficient ubiquitin ligase activity that does not induce mitophagy [34, 41].