Since perturbations of Ca2+ homeostasis in MNs have been often claimed as a crucial event in disease progression7, 23 we tested the applicability of the novel Ca2+-probe encoding vectors to the comparative analysis of local Ca2+ homeostasis in MNs from an ALS mouse model [i.e., mice expressing the ALS-related G93A mutant of human (h) SOD1 and the healthy counterpart (hSOD1(WT)-expressing mice)]. The gene discussed is SOD1; the disease is amyotrophic lateral sclerosis.