Deubiquitinases (DUBs) are a class of enzymes that are able to reverse the process of ubiquitination.1 Extensive research has revealed that there are more than 100 DUBs found in humans, which are classified into seven main families: ubiquitin-specific proteases (USPs), ubiquitin carboxyl-terminal hydrolases, the Machado-Joseph disease domain superfamily, the otubain/ovarian tumor-domain containing proteins, the ZUFSP (Zinc finger with UFM1-specific peptidase domain protein) family, the JAB1/MPN/MOV34 proteases, and the novel motif interacting with ubiquitin-containing DUB family. All DUBs are cysteine proteases, except the JAB1/MPN/MOV34 proteases, which are Zn2+ metalloproteases.1 The family with the largest number is the USPs. These enzymes remove the ubiquitin molecule from the larger protein, which leads to protein stability and protection from proteasome degradation. Many USPs have been demonstrated to be closely linked with the proliferation and metastasis of tumor cells, as well as facilitating tumor immune evasion.1 More importantly, inhibitors targeting USPs have become a hot topic in tumor therapy, showing promising prospects.1