In this week's PNAS Early Edition, researchers at the University of Washington, Sage Bionetworks, and Pacific Biosciences report their use of "both time-series data and genetics data to infer directionality of edges in regulatory networks: time-series data contain information about the chronological order of regulatory events and genetics data allow us to map DNA variations to variations at the RNA level." The Washington-led team generated microarray data measuring time-dependent gen