USP2 and cancer: Furthermore, in the past few decades, a large number of drugs or inhibitors targeting UBRs (such as TRAF6, LUBAC, USP1, USP2, USP7, USP8, and USP9X) have been developed, and some drugs or inhibitors targeting UBRs, such as thalidomide, pomalidomide, and lenalidomide, have been approved by the FDA for the treatment of cancer [30].