'Goldilocks' suppressor screen identifies web of polarity regulators.

Genome sequencing and RNAi have been powerful allies in the quest to assign function to every gene. Systematic RNAi screens identify essential genes efficiently, but are less effective with pleiotropic or redundant genes. A common trick used by geneticists to overcome this problem is to screen for genetic interactors - mutations that enhance or suppress the phenotype of a starting mutation. Now, this classic approach has been combined with the versatility of RNAi to generate an expanded gene network for cell polarity.