Subsequently, two other proteasome inhibitors, the peptide epoxyketone carfilzomib (KYPROLISTM) and the boronic acid ixazomib (NINLAROTM) have been added to the cancer treatment armamentarium, and we have also learned that other classes of anti-cancer therapeutics such as immunomodulatory drugs (IMiDs–e.g., thalidomide, lenalidomide, and pomalidomide) exert their therapeutic effect via targeting of the UPS [4]. This evidence concerns the gene HMBS and cancer.