WWTR1 and neoplasm: Our findings expand the list of E3 ubiquitin ligases involved in regulating YAP/TAZ protein degradation in the context of tumor growth to MIB2 and show that in FAT1-expressing tumor cells MIB2 is centrally involved in controlling YAP/TAZ protein levels and YAP/TAZ downstream signaling and that the FAT1/MIB2 pathway functions as a critical tumor suppressor.