Endoplasmic Reticulum (ER) stress is associated with a variety of pathophysiological conditions, such as neurodegenerative diseases, diabetes, tumor growth under hypoxic conditions, and ischemic heart disease. Proteins in the ER misfold or unfold, and accumulate under stress conditions, which promote the expression of ER stress responsive genes. One of the mechanisms for mediating ER stress response is the activation of transcription factor ATF6. The quiescent form of ATF6 (p90ATF6), a type II-transmembrane protein, is embedded in the ER membrane and proteolyzed in an ER stress-dependent manner. The liberated N-terminal fragment (p50ATF6) translocates to the nucleus, binding to ER stress response element (ERSE) present in the proximal promoter regions of many ER stress-responsive proteins including ER chaperones. To better understand the pathological processes and provide novel avenues to potential therapies, ESRE–bla HeLa cells are engineered to express beta-lactamase under the control of ER stress response element. This is a clonal population isolated by FACS and its dose response curves with tunicamycin and thapsigargin are performed. This cell line also response to other known ER stress inducers.