Much of the work on ER stress in CF has been conducted by the Ribeiro group at University of North Carolina, and they have recently reviewed ER stress and UPR activation in CF.46 The most instructive data on the contribution of CFTR mutations to ER stress emanate from studies of cultured human bronchial epithelial cells (HBECs) derived from CF patients and healthy donors, separating the cells with the intrinsic defect from the inflamed and infected in vivo environment in the disease. The gene discussed is CFTR; the disease is cystic fibrosis.