S¨ uel, G. M., Garc´ıa-Ojalvo, J., Liberman, L. M., Elowitz, M. B., 2006. An excitable gene regulatory circuit induces transient cellular differentiation. Nature 440, 545–550. Swiers, G., Patient, R., Loose, M., 2006. Genetic regulatory networks programming hematopoietic stem cells and erythroid lineage specification. Dev. Biol. 294, 525–540. Tyson, J. J., Chen, K. C., Novak, B., 2003. Sniffers, buzzers, toggles and blinkers: dy- namics of regulatory and signaling pathways in the cell. Curr. Opin. 15, 221–231. Ullner, E., Zaikin, A., Volkov, E. I., Garc´ıa-Ojalvo, J., 2007. Multistability and clustering in a population of synthetic genetic oscillators via phase-repulsive cell-to-cell communi- cation. Phys. Rev. Lett. 99, 148103. Williams, J. G., 2006. Transcriptional regulation of Dictyostelium pattern formation. EMBO Rep. 7, 694–698. 20