JAG1 and breast cancer: In the breast epithelium primary tumor, hypoxia induces the loss of some epithelial characteristics via Jagged1(JAG1)/Notch activation in the breast cancer stem cells (BCSCs) (Al-Hajj and Clarke, 2004; Martin et al., 2005; Leong et al., 2007; Sahlgren et al., 2008; Gangopadhyay et al., 2013; Shao et al., 2015) (Figure 5B).