ZEB1 and glioblastoma: To confirm ZEB1 loss at the protein level, we performed immunohistochemistry using tissue microarrays (Fig. 2b), which revealed the presence (Fig. 2bb and bd) and absence (Fig. 2ba and bc) of ZEB1 when compared to control (Fig. 2be) in grade 4 GBMs consistent with the loss of ZEB1 in certain patients and the preservation of ZEB1 in other GBM patients.