USP7 and breast cancer: USP7, a member of the USP family, is first defined as Herpes virus associated cellular factor (HAUSP) and is critical for genome stability, epigenetic regulation, cell cycle, apoptosis, viral infection immunity and stem cell maintenance.16, 17, 18, 19, 20 Clinically, USP7 is reportedly associated with tumorigenesis, including prostate cancer, multiple myeloma cancer, ovarian cancer, breast cancer and NSCLC.20, 21, 22, 23, 24