Picture of the regulatory network obtained when all leaf nodes in the network of Fig. 1 are removed along with all their links. The colour coding of all nodes is as in Fig. 1. The red hexagon denotes the lone TF in the network that is coded for by two genes. The nomenclature for conditions C1 to C7 and S1 to S8 is given in Table S4 in Additional File 1. The electronic version of this figure can be zoomed in to read node names.