Chromobox protein homolog 8 is a protein that in humans is encoded by the CBX8 gene.CBX8 has been shown to interact with RING1 and MLLT1.Component of a Polycomb group (PcG) multiprotein PRC1-like complex, a complex class required to maintain the transcriptionally repressive state of many genes, including Hox genes, throughout development. PcG PRC1 complex acts via chromatin remodeling and modification of histones; it mediates monoubiquitination of histone H2A 'Lys-119', rendering chromatin heritably changed in its expressibility.