Infection with Fgf13-S in a Gad2Fgf13 KO neuron showed concentrated expression in the axon initial segment and membrane-enriched signal in the soma and the dendritic branches (Figure 6A) while infection with Fgf13-VY produced prominent signal throughout the soma and branches, demonstrating successful re-expression of these splice variants in the knockout background. Here, FGF13 is linked to infection.