The importance of cellular excitability for motoneuron survival and function is strengthened by recent reports on the voltage-gated sodium channel Nav1.9 which significantly contributes to motoneuron axon growth on laminin-111 (Subramanian et al., 2012; Wetzel et al., 2013) and the loss of the potassium channels Kv2.1 which corresponds to motoneuron degeneration in SMA mouse models (Fletcher et al., 2017). Here, KCNB1 is linked to proximal spinal muscular atrophy.