The high promiscuity of this NUB1-mediated substrate turnover and FAT10 expression in immune cells upon inflammation, viral infection and in multiple cancers could make the specific FAT10-ylation of neosubstrates for proteasomal degradation an attractive alternative to the proteolysis-targeting chimera (PROTAC) technology, which typically relies on small-molecule-induced ubiquitination and frequently requires p97 to prepare well-folded proteins for proteasomal engagement. This evidence concerns the gene UBD and viral infectious disease.