Interestingly, Notch signaling in HER2- breast CTCs has been reported to mediate chemoresistance (Jordan et al., 2016) while, a contradicting study has signified the role of Notch1 in mediating CSC survival in HER2+ breast cancer (Baker et al., 2018), further pointing towards the complexity and pleotropicity of Notch signaling in cancer. This evidence concerns the gene NOTCH1 and breast cancer.