The mechanisms underlying the AGR2-associated tumor promotion in the biliary tract cancer cells and the observed discrepancy in the tumor promoting potential of AGR2 in different cells remain to be elucidated in future studies in which AGR2 knockdown SNU-478 or AGR2 overexpressing SNU-869 could be utilized as a valuable model system. The gene discussed is AGR2; the disease is biliary tract neoplasm.