O00257

CBX4 suitable for the detection of the CBX4 protein. Polycomb group (PcG) proteins form multiprotein complexes and play a role in gene silencing (1,2) and Hox gene regulation by altering chromatin structure during transcription. The PcG protein CBX4, also known as, PC2 or NBP16, maps to human chromosome 17q25.3. CBX4 and CBX8 are PcG proteins that show structural similarity to M33 and, like M33, bind the PcG protein RING1 through a conserved c-box motif located in the C-terminus of RING1 (1,2,5). CBX4 is a repressor of proto-oncogene activity, thus interference with CBX4 function can lead to depression of proto-oncogene transcription and subsequently to cellular transformation. CBX4 is able to act as a long range transcriptional silencer (1,7). CBX4 is expressed in the human osteosarcoma cell line U-20S. CBX4 is part of a large multiprotein complex that also contains other PcG proteins including Bmi-1 (1,7).