KRT14 and cancer: The histological examination of GFP expression in cancer cells showed that the CreERT2 fusion protein was active in a subset of cells within tumors that had retained an expression of CK8 (Fig. 6C, left) as well as the majority of cancer cells that acquired basal and mesenchymal-like characteristics, i.e., those that were CK14-positive or lacked cytokeratin expression (Fig. 6C, right).