Has transcriptional repressor activity, probably as part of a complex with YY1, SIN3A AND HDAC1 (PubMed:21454521). Required for B cell lymphopoiesis (PubMed:20530203). Found in a complex with YY1, SIN3A and HDAC1. Expressed in thymus. Specifically expressed in B cells and their precursors (at protein level). Also detected in brain, heart, spleen and bone marrow. Chimeric cDNA.