PTEN and breast cancer: In contrast, HAUSP, ataxin-3, USP13, and OTUD3 have all been identified recently as PTEN deubiquitinases (DUBs): HAUSP specifically removes the mono-ubiquitination of PTEN for its nuclear export17, ataxin-3 regulates PTEN at the transcriptional level18, and USP13 and OTUD3, which predominantly reside in the cytoplasm, affect cytosolic PTEN stability in a breast cancer-specific context19,20.