Role of BCOR and noncanonical PRC1.1 complex in the germinal centers of B-cell follicles. Mantle naïve B cells do not express BCL6. Germinal center B cells strongly express BCL6 (nuclear brown positivity at immunoperoxidase staining with monoclonal antibody PG-B6p⁴²). BCL6 interacts with BCOR to recruits the PRC1.1 that leads to the epigenetic transcriptional repression of BCL6 target genes. CBX8 is also a component of the complex in the germinal center B cells.² The white asterisk indicates recruitment of PRC2 to the ubiquitinated loci. In addition to BCOR, the POZ domain of BCL6 also interacts with the SMRT and N-CoR corepressors that are part of the large multiprotein histone deacetylase-containing complexes and are also required for the repressive activity of BCL6. These events result into the temporary silencing of genes controlling differentiation of B cells to plasma cells and cell cycle checkpoint (CDKN1A, CDKN1B) to allow immunoglobulin affinity maturation. B cells that exit from germinal center downregulate BCL6 before giving raise to plasma cells and memory B cells.