Polycomb group RING finger protein 6 (PCGF6 or MBLR) is a transcriptional repressor []. It may activate KDM5D histone demethylase, which modulates the levels of histone H3K4Me3 []. PCGF6 is a component of the Polycomb group (PcG) multiprotein PRC1-like complex [], in which it regulates RNF2 ubiquitin ligase activity [], and the E2F6.com-1 complex []. PCGF6 contains a RING-type zinc finger.