Transcription factor genes most highly expressed by each monocyte subset and the analysis of their protein-protein interactions. Transcription factors most highly expressed by (A) classical, (B) intermediate, and (C) nonclassical subsets are shown. The normalized log₂ MFIs for each gene are illustrated in corresponding heat maps. Possible known direct protein-protein interactions between the transcription factors most highly expressed by the (D) classical, (E) nonclassical, and (F) the intermediate plus nonclassical subset combined were revealed using Ingenuity Pathway Analysis. Common transcription factor genes found in panels E and F are highlighted. Lines represent direct protein-protein interactions; loops, homodimerization; and arrows, direct increase in expression.