Examples of network motifs (a,c) and themes (b,d). (a,b) A transcriptional feed-forward motif that occurs repeatedly in the control of the cell cycle. (c,d) Two targets of transcription that are regulated by co-expression, protein-protein interaction or homology during periodic histone gene expression. Images reproduced from .
Weitzman Journal of Biology 2005 4:4 doi:10.1186/jbiol25