KRT18 and cancer: Post-translational modification, up- or down-regulation of tumor biomarkers, such as CK18 protein in tumor cells revealed and quantified by phenotypic immunostaining, correlates with cancer progression [19], cell migration [20], and differentiation in hepatocellular carcinoma (HCC) [21], as well as with staging, metastasis and recurrence in esophageal squamous cell, renal cell, breast, and nasopharyngeal carcinomas [18].