SUZ12 also known as ChET9 is a nuclear protein belonging to the VEFS (VRN2-EMF2-FIS2-SUZ12) family. SUZ12 plays a crucial role in the Polycomb group (PcG) complex, which is essential for maintaining cell identity and regulating gene expression during development and differentiation. SUZ12 functions as a key component of the PRC2 complex, which also includes EED, EZH2, RBBP4, and RBBP7, and is involved in the trimethylation of histone H3 at lysine 27 (H3K27me3), a modification critical for gene silencing and chromatin remodeling. This post-translational modification is vital for proper regulation of developmental genes and maintenance of stem cell pluripotency, as H3K27me3 helps establish a repressive chromatin state that prevents expression of genes that could lead to differentiation.