May be involved in transcriptional regulation. Overexpression causes down-regulation of a number of genes involved in the immune response. Some genes are also up-regulated. Detected in spleen and thymus but not in liver, muscle, heart, kidney, brain, bone marrow or pancreas. Expressed in CD19+, CD4+ and CD8+ lymphocytes but not in CD11b+ lymphocytes or peritoneal macrophages (at protein level). Up-regulated during the transition from CD4-/CD8- to CD4+/CD8+ thymocytes.