HEXB and Salla disease: Previously identified activation of two vital potentiators of ER stress during SD progression led us to evaluate the intracellular localization of the executioner caspase cleaved caspase 7 (cCas7), temporally in the spinal cords of Hexb+/+ and Hexb−/− mice, to determine a timeline of the mass neuronal death known to be associated with SD pathology.