USP7 and cancer: Moreover, USP7 also plays an important role in regulating host immune response against cancer, and a recent study reported that P5091, a USP7 selective inhibitor effectively inhibited the growth of colon carcinoma xenografts through enhancing anticancer immunity via decrease of FOXP3-positive T regulatory cells (Treg) in tumor bearing mice [16], indicating USP7 inhibition may also potentially boost the host antitumor immunity.