An intriguing finding to recently emerge from plant research is that some transcription factors, such as the Arabidopsis thaliana floral identity protein LEAFY (LFY), can move between cells. On p. 3735, Wu et al. use functional GFP fusion proteins to investigate the mechanisms underlying such movement in the Arabidopsis shoot apical meristem (SAM) and floral primordia. Their findings reveal that the localization of a protein,such as that of LFY, can determine its ability to move – for example,nuclear localization appears to prevent untargeted protein movement –and that such movement probably occurs through simple diffusion. Differences in within-layer and between-layer protein movement are also evident, with between-layer movement being more prevalent in the SAM. Their findings lead the authors to propose that many macromolecules might move through the SAM by default, unless specifically retained through their subcellular localization.