PSEN1 and Alzheimer disease: The genetic deletion of EP1 receptor decreased basal levels of Aβ in Swedish amyloid precursor protein (APPS)/presenilin-1 (PS1) mice model (APPS- and PS1-mutated AD model), and therefore, neurons in the absence of EP1 receptor are presumably more resistant to Aβ-induced toxicity (Zhen et al., 2012).