Activity dependence of BoNT/D uptake into hiPSC derived Neurons. A: iCell Neurons were exposed to 10,000 U of BoNT/D at 37°C in either culture media (CM) or cell stimulation media (CSM) containing 56 mM KCl and 2.2 mM CaCl2. Cells were harvested every hour at from 0 to 8 h, and cell lysates analyzed for VAMP2 in relation to syntaxin by Western blot and densitometry. B: iCell Neurons were exposed to serial dilution of BoNT/D in either culture media (CM) or cell stimulation media (CSM) containing 56 mM KCl and 2.2 mM CaCl2 for 10 min. at 37°C. All toxin was removed, cells washed, and incubated further in culture media. Cells were harvested after 16 h, and cell lysates analyzed for VAMP2 in relation to syntaxin by Western blot and densitometry. The graphs depict quantitative data from triplicate samples, respectively.