Experimental setup and regulome profile of the human SPI1 locus. (A) Isolation scheme for monocyte subsets, sort gates for the FACS purification, and reanalysis of the 3 CD14/CD16-stained monocyte subsets are shown (1 representative out of 3 independent experiments). (B) Genome browser tracks covering the human SPI1 locus of available epigenetic (H3K4me1 and H3K27ac) and HeliScopeCAGE data (coloring indicates monocyte subtypes: classical, red; intermediate, green; nonclassical, blue). All 3 subsets equally express the myeloid master regulator PU.1, and the 2 major subsets show strikingly similar epigenetic profiles across the locus. The second CAGE peak at right corresponds to the position of the conserved upstream enhancer, well characterized in mice.¹⁹