S100B and amyotrophic lateral sclerosis: Because S100B acts as a Ca2+ sensor protein to regulate Ca2+ homeostasis within terminal Schwann cells and increased intracellular calcium is regarded as a common denominator in motor neuron injury in ALS [37], a possible speculation is that changes in Ca2+ homeostasis might be involved in the breakdown of the nerve-muscle contact at the NMJs in ALS.