PRB2 and Alzheimer disease: In this line, PS1, 2 deficiency (absence of PS proteins or AD-associated mutation) is capable of impairing cellular calcium homeostasis of the endoplasmic reticulum (ER) and lysosomes (Coen et al., 2012, Popugaeva and Bezprozvanny, 2013, Tu et al., 2006) and its lysosomal function (Dobrowolski et al., 2012, Lee et al., 2010, Neely et al., 2011).