The ability to test, on a large scale, the phenotypic consequences of treating cells with large numbers of genetic or chemical perturbations represents a substantial new asset in the cell biologists’ toolbox. Academic biologists, interested in a specific function, can systematically knock-down the expression of all the genes in a genome to identify those whose alteration modifies a specific functional readout. Application-oriented scientists, on the other hand, can screen a large number of chemicals to identify potential drug leads that revert a pathological phenotype. Thus, many academic and non-profit organizations are exploring these new high-content phenotypic approaches for medium-to-large gene screening or drug discovery programs. As ...