A small ensemble of musicians can produce an infinite number of melodies, harmonies and rhythms. So too, do a handful of workhorse signaling pathways that interact to construct multiple structures that comprise the vertebrate body. In fact, crosstalk between two of those pathways -- those governed by proteins known as Notch and BMP (for Bone Morphogenetic Protein) receptors -- occurs over and over in processes as diverse as forming a tooth, sculpting a heart valve and building a brain.