Fig. 5. Selected regulatory interactions among early specification genes and late transcriptional regulators in the micromere-PMC GRN. This schematic is based on the work of Oliveri et al. (Oliveri et al., 2008), although certain gene interactions have been omitted from their GRN, either for clarity or because the data supporting the links are equivocal. Yellow boxes indicate early specification genes and red boxes indicate late transcriptional regulators. Two of the early specification genes shown (ets1 and tbr) are also expressed maternally (indicated by stippling). The interactions shown are based on morpholino knockdown studies and may be indirect. Arrows indicate positive interactions and bars indicate negative interactions.