KRT14 and breast cancer: Cheung and colleagues found that Keratin 14, an epithelial cytoskeletal protein, is highly expressed in murine breast cancer CTC clusters and that these Keratin 14 positive cells exhibit a hybrid E/M phenotype expressing both epithelial and EMT/stemness mesenchymal markers (Cheung et al., 2016), again indicating that plasticity may be a key feature for survival of tumor cells that leave the primary tumor.