Smn knockdown in primary cultured motor neurons after magnetofection with an shRNA construct. Primary motor neurons were transfected with an Smn-specific (top) or control shRNA plasmid (bottom) for 5 days. Transfected cells were identified by EGFP expression (green). Anti-Smn antibody staining (red) was used to evaluate Smn protein levels. Fluorescence intensity was quantified in the cell body and axon using the Imaris software and normalized to the axon volume. Smn protein levels were reduced in both cell body and axon when the Smn-specific shRNA was used, in comparison to the control shRNA construct. Bars represent mean and SEM. One way ANOVA, n = 3; ***p < 0.001, **p < 0.01. Size bar: 10 μm.