There was an error in the legend for Figure 1. The correct Figure 1 legend is: A. Schematic of the method used to delete agrin from subsets of motoneurons. In the SLICKA transgene, separate Thy1 regulatory elements drive expression of CreER and YFP. Following administration of tamoxifen, CreER is activated and the agrin gene is deleted in many YFP+ motoneurons. B. A YFP+ motor axon (green) in a triangularis sterni muscle. Unlabeled axons are stained with neurofilament and syntaptotagmin 2 (red) to mark all nerve terminals. Scale bar = 100 µm. C. Agrin (red) at NMJs (green) in control (agrn+/flox; SLICKA) and mutant (agrn-/flox; SLICKA) muscle at the indicated times after tamoxifen (TX) administration. Agrin levels are decreased slightly 1 month after TX and markedly by 3 months. Scale bar = 10 µm. TX = tamoxifen
