ZEB1 and cancer: The reduction of cancer cell-specific Zeb1 protein expression was confirmed through immunolabeling of the primary tumor in both the KPPC;ZF+ and the KPPC; Zeb1cKO (Figures S6A and S6B) as well as quantified with the co-expression of mesenchymal markers and the lineage tracer YFP (Figure 6H).