Auxin is a hormone that is essential for the development of plants as it controls a wide range of processes from shaping the embryo in the seed to branching of the growing plant. Previously, it was believed that auxin’s main signaling mechanism operated in the cell nucleus and acted only by regulating gene transcription. Now, scientists led by Jiří Friml at the Institute of Science and Technology Austria (IST Austria) have demonstrated that another mechanism exists, and that cells in the roots must be able to respond to auxin immediately. This mechanism enables rapid adaption of root growth direction.