BAP1 also known as UCHL2 belongs to the ubiquitin C-terminal hydrolase subfamily of deubiquitinating enzymes that are involved in the removal of ubiquitin from proteins. BAP1 plays a significant role in the regulation of protein degradation and cellular signaling pathways. This function is vital for maintaining cellular homeostasis and preventing tumorigenesis, as BAP1 helps to modulate the activity of various substrates involved in cell cycle regulation and DNA repair. The interaction of BAP1 with BRCA1 is particularly important, as BAP1 enhances BRCA1-mediated cell growth suppression, thereby contributing to the tumor-suppressive functions of the BRCA1-BAP1 complex. Additionally, BAP1 interacts with several other proteins, including the histone deubiquitinase complex, which further underscores BAP1′s role in epigenetic regulation and cancer biology.