ERN1 and susceptibility to pneumonia measurement: The ER stress response has an important role in the pathogenesis and exacerbation of several diseases, including cancer, pneumonia, and neurological diseases; three ER stress sensors are known: protein kinase R-like ER kinase (PERK), inositol-requiring enzyme-1 (IRE1), and ATF6, through which the unfolded protein response is induced [33,34].