Fluorescent protein-tagged Smn is localized and actively transported in the axons of primary motor neurons after magnetofection. A. Full-length Smn fused to the N- (top) or C-terminus (bottom) of EGFP or mCherry fluorescent proteins (FP) was tested in order to exclude artefacts caused by the fusion partner. Compressed deconvolved 3-D image stacks show Smn-positive gems in the nucleus (arrows) and small granules localized along the axon (arrowheads). DAPI staining (blue) identifies nuclei. B. Live cell imaging of Smn-mCherry granules. Single snapshots of a representative Smn-positive granule moving anterogradely toward the growth cone (star) are shown. The granule moved 50.05 μm with an average speed of 1.80 μm/sec. Size bars: 10 μm in A, 15 μm in B.