For example, recently non-CSCs of human basal breast cancer were shown to be able to switch to a CSC state as a result of ZEB1 activation.39 Plasticity of these cells involved a bivalent chromatin configuration of the ZEB1 promoter, allowing an effective transcriptional response to microenvironmental signals as was shown toward TGFβ in this model. This evidence concerns the gene ZEB1 and breast cancer.