PVALB and amyotrophic lateral sclerosis: First, motoneurons preferentially express glutamate receptors, such as the AMPA receptors, which are more permeable to influx of Ca2+ ions (Kawahara et al., 2004), and motoneurons in ALS patients lack the intracellular expression of Ca2+ binding proteins parvalbumin and calbindin D28k, both required to buffer intracellular Ca2+ (Alexianu et al., 1994).