Ubiquitin fusion degradation protein 1 homolog (UFD1) forms a dimer with Npl4 (nuclear protein localization 4) and can associate with the ATPase, p97/VCP, to form a ternary complex involved in the ubiquitin-proteasome pathway. The UFD1-p97-Npl4 complex functions to recognize ubiquitin-tagged proteins and facilitate their presentation to the 26S proteasome for degradation. This ternary complex has also been shown to play an important role in mitotic spindle disassembly. Hemizygosity in the gene which encodes UFD1 (UFD1L) is the cause of some catch 22-associated developmental defects. Additionally, the UFD1L gene has also been implicated in the neurodevelopment al origin of schizophrenia.