Polycomb-group (PcG) proteins form multimeric complexes that maintain the state of transcriptional repression of several regulatory genes during development. Ring1B/Rnf2 forms part of a protein complex containing other PcG proteins, such as Mel18, Bmi1, MBLR, MPc3, and the spliceosome protein Sap155, and these complexes associate with chromatin to regulate transcription. Ring1B may also play a role in the regulation of Hox gene expression by PcG complexes. Deletion of Ring1B activity results in gastrulation arrest and cell cycle inhibition.Synonyms: BAP-1, BAP1, DING, E3 ubiquitin-protein ligase RING2, HIP2-interacting protein 3, HIPI3, Protein DinG, RING finger protein 2, RING1B