TGFB1 and breast carcinoma: 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.