I&#x27;m not sure they exist yet; we&#x27;re still at the stage where we are trying to appreciate the complexity of the systems we are studying. The first step is to catalog. For example we&#x27;ve only recently begun to appreciate the extent of genetic heterogeneity in cancers (and the therapeutic significance of this variation). Now that we have this sense people are beginning to think about new experimental methods for collecting this kind of information; we are still a few years (maybe a decade) out from good models of how to analyze it.