ATF4 and neoplasm: To confirm the role of ATF4 in the anticancer effectiveness of gemcitabine in pancreatic xenografted tumor models in vivo, we performed an intraperitoneal injection of gemcitabine at a concentration of 100 mg/kg twice a week one week after subcutaneous xenotransplanted tumor models were established successfully with PANC-1 shATF4 or PANC-1 shNC cells.