PHC2 (polyhomeotic homolog 2) is a core component of Polycomb repressive complex 1 (PRC1) that plays essential roles in transcriptional repression and chr1 regulation 1. PHC2 functions by binding to BMI1 through a β-hairpin conformation, which is necessary for H2A ubiquitination activity and proper PRC1 function 1. The protein contributes to PRC1 condensate formation, where it acts synergistically with chr1 to reduce the critical concentration required for condensation by more than 20-fold 2. PHC2's polymerization activity specifically influences condensate dynamics by promoting the formation of distinct domains that maintain stability without coalescence 2. Beyond its classical role in gene silencing, PHC2 participates in DNA damage response by cooperating with nucleoporins to promote transcriptional repression at DNA double-strand breaks, with its presence at DSB sites being interdependent with nucleoporins 3. PHC2 belongs to a family of three mammalian polyhomeotic homologues, sharing highly conserved domains particularly with PHC3, and showing ubiquitous expression during development 4. The protein has been identified as part of an immune-related gene signature with potential diagnostic value for acute myocardial infarction 5.