POU5F1 and gastric cancer: Coexpression of OCT4 and NANOG stimulates CSC properties and invasiveness through Stat3/ Snail signaling in hepatocellular carcinoma, while the knockdown of OCT4 decreases invasiveness in pancreatic and gastric cancer cells (Chiou et al., 2010; Zheng-jie et al., 2012; Lin et al., 2014).