USP4 and hepatocellular carcinoma: For instance, Wang et al. found that the high expression of circRHOT1 was associated with poor prognosis of hepatocellular carcinoma (HCC), and confirmed that circRHOT1 promoted malignant progression of tumors [13], Liang et al. discovered a new circRNA from breast cancer tissues, named circBMPR2, and identified its role in inhibiting cell proliferation, migration, invasion and tamoxifen resistance by regulating the circBMPR2/miR-553/USP4 axis [14].