DNA transfection reagent facilitates rapid BoNT/A internalization by N2A cells and the extent of intoxication is toxin concentration dependent. A. N2A cells were exposed to 10 nM BoNT/A toxin for 0.5, 1, 2, 3, 6 or 24 hrs with (+) or without (−) pre-incubation of toxin with FuGene-HD transfection reagent and immediately harvested. B. BoNT/A toxin was pre-incubated with FuGene-HD then added to N2A cells at 10 nM for 0.5, 1, 2, 3, 6 or 24 hrs. Medium was changed and all the cells were cultured until 48 hrs after initial toxin exposure. C. N2A cells were exposed to 10 nM, 1 nM and 0.1 nM of BoNT/A toxin for 24 hrs with (+) or without (−) pre-incubation with FuGene-HD transfection reagent and then harvested. D. N2A cells were exposed to 10 nM, 1 nM and 0.1 nM of BoNT/A toxin for 3 hrs in the presence of FuGene-HD transfection reagent and then harvested. Cell extracts were prepared and resolved by SDS-PAGE. The extent of BoNT/A intoxication was measured by Western blotting to assess the extent of SNAP25 cleavage.