Epigenetic priming of T cell–specific gene promoters in early hematopoiesis. T cell–specific genes were selected from the literature and their promoters analyzed for the presence of activating (green) or silencing (orange) histone modifications, PolII (teal), or no marks (gray) in HSCs, MPPs, PreMegEs. and T cells. Genes were grouped according to lineage-associated functions: T cells, B cells; cell surface signaling receptors, granulocyte/monocytes (GM); myeloid/lymphoid cells (My/Ly), hematopoietic stem cells/megakaryocytes and erythrocytes (HSC/MegE). Gene expression values are shown as a heat map using a cutoff value of 50 (white) to determine genes with no detectable expression (blue) and expressed genes (red).