NFE2L2 and amyotrophic lateral sclerosis: Similarly, some studies have also found that in skeletal muscle of an ALS mouse model, increased Nrf2 levels occur at very early time points, even before the onset of movement impairments (Kraft et al. 2007), which may provide support for the hypothesis of motor neuron degeneration starting at the level of the neuromuscular junction (Pavlovskiĭ and Mikaĭlenko 1976).