AGR2 and lung cancer: Our study emerged from three pieces of currently available knowledge about AGR2 and ZEB1: a) AGR2, similarly to all epithelial proteins, is downregulated during the EMT process [24]; b) upregulation of the EMT-associated transcription factor (EMT-TF) ZEB1 represses the expression of epithelial proteins, among which E-cadherin serves as a prominent example of ZEB1 targets [5]; and c) AGR2 protein is overexpressed in various solid malignancies including lung cancer [23,25].