Evidence that dysfunctional dynein/dynactin mediated axonal transport is sufficient to cause motor neuron degeneration first came to light when LaMonte et al. showed that disruption of dynein/dynactin interaction by postnatal overexpression of p50/dynamitin, a 50-kDa subunit of dynactin encoded by DCTN2, caused reduced axonal transport in motor neurons and consequently led to a late-onset progressive motor neuron disease phenotype in the transgenic mice (LaMonte et al., 2002). The gene discussed is DCTN2; the disease is motor neuron disorder.