A bit more on network motifs:

A taxonomy of network motifs exists. For some clear descriptions and diagrams, see Network motifs. This page describes gene regulation, but it's not too hard to extrapolate from motifs like "autoregulatory", "feedforward", "multi-component loop", etc.

To understand how complex transcriptional regulatory networks produce gene expression programs, it is useful to identify the simplest units of commonly used network architecture. We imagine that these simple units, or network motifs, provide specific regulatory capacities such as positive and negative feedback loops. The frequency with which cells use individual motifs reveals the regulatory strategies that were selected during evolution. These motifs can be assembled into network structures that help explain how a complex gene expression program is regulated.

(from site above).