Our latest work on the formation of Shh morphogen source (floor plate) in the growing spinal cord is now available at: https://www.biorxiv.org/content/10.1101/2024.03.01.582751v1. By supporting computational results with experiments @Kicheva Lab we showed that the floor plate is formed in two distinct phases: rapid formation through gene regulatory interactions, followed by passive expansion by tissue growth. This result might be of general relevance for pattern formation in growing organs.