ERN1 and bacterial infectious disease: Changes in the microenvironment due to physiological processes or to pathological conditions, such as hypoxia, viral, or bacterial infections and drugs, can induce ER stress, thus causing GRP78 to separate from the sensors (PERK, IRE1, and ATF6) and further activate downstream signaling (Hollien and Weissman, 2006; Díaz-Bulnes et al., 2020; Kapadia et al., 2021; Mazel-Sanchez et al., 2021).