FIGURE 1 

The classical approach (blue arrows, top) for deciphering transcription network is to start with expression data typically gathered at multiple time points during a process or in different tissues (left), to cluster coexpressed genes along the time profile (middle), and then to look for shared motifs within each cluster (right). In the approach (red arrows bottom) developed by Das et al in human cells, and described in previous works in yeast (Bussemaker et al, 2001; Pilpel et al, 2001), the process is reversed—starting from known motifs, and by-passing the clustering stage, motifs or combinations thereof are analyzed for their impact on gene expression under a specific condition (time point, tissue, treatment, etc.).