In the PNAS Early Edition this week, Cold Spring Harbor Laboratory's Scott Lowe and his colleagues "demonstrate the feasibility of transgenic inducible RNAi for suppression of essential genes." In an adult mouse model, Lowe's team targeted cell proliferation by screening an RNAi library against DNA replication factors; the group identified multiple short hairpin RNAs against Replication Protein A, subunit 3 — RPA3 — and, subsequently, "generated transgenic mice with TRE-driven Rpa3 shRNAs whose expression enforced a reversible cell cycle arrest," it writes.