A second objection might be that prioritizing candidate interactions requires the corresponding Y2H baits and preys to be rearrayed in microtiter plates in different orders over the course of an interaction mapping project. While the cost of rearraying was not included in our analysis, in our lab (Finley) these costs are greatly alleviated through robotic transfer systems. Certainly, failure to rearray leads to a ~4-fold increase in cost and a ~10fold increase in the early stages of mapping (compare Pooling versus Prediction in Table 1 ).