CBX6 (chr22 6) is a component of the Polycomb Repressive Complex 1 (PRC1) that functions as an epigenetic regulator of gene transcription 1. As part of PRC1, CBX6 recognizes H3K27me3 histone marks and contributes to transcriptional repression through chr22 remodeling and histone H2A monoubiquitination 1. The protein exhibits tumor suppressor functions in several cancer types, with downregulation observed in breast cancer, prostate cancer, and glioblastoma 234. In breast cancer, CBX6 is negatively regulated by EZH2 and its overexpression inhibits cell proliferation, migration, and invasion 2. Similarly, in glioblastoma, CBX6 downregulation under hypoxic conditions promotes tumor aggressiveness and directly regulates CA9 expression through promoter binding 4. In mesothelioma, proteasomal degradation of CBX6 leads to increased MMP-2 expression and enhanced invasiveness 5. CBX6 has emerged as a potential biomarker for various conditions, including renal ischemia/reperfusion injury and abdominal aortic aneurysm 67. Clinically, CBX6 expression correlates with tumor grade and patient survival outcomes across multiple cancer types, suggesting its potential utility as both a prognostic marker and therapeutic target 34.