English: HCA undergoes fast retrograde axonal transport in primary motor neurons in MFC. Motor neurons grown in MFC were incubated with fluorescent HCA for 30 min at 37°C in resting conditions, then washed and imaged by time-lapse confocal microscopy. The toxin was added exclusively to the axonal side. Cell body is out of view on the right. Frames were taken every 3 s and the movie plays at 5 frames/s. This movie is a representative example of experiments performed on two independent primary motor neuron cultures, replicated three times.