The conservation of transcription factor production and target gene expression in a given cell type. This cartoon representation shows such conservation of gene expression driven by a lineage-specific arrangement of bound transcription factors (colored ovals). The arrow indicates gene expression. The factors expressed in the ancestral cell can be inferred, but the cis-regulatory arrangement cannot.
Malone and Oliver Journal of Biology 2009 8:32 doi:10.1186/jbiol131