POU5F1 and gastric cancer: Another example is hypoxia, which also maintains a stem-like phenotype in CRC and GC through the increased expression of hypoxia-inducible factors (HIFs), the transcription factors HIF-1α and HIF-2α, that maintain the Wnt/β-catenin signaling pathway and activate stemness-related TFs such as OCT4 (Gidekel et al., 2003; Liu et al., 2008; Mazumdar et al., 2010; Yeung et al., 2011; Vadde et al., 2017).