PLK1 and esophageal squamous cell carcinoma: Interestingly, in esophageal squamous cell carcinoma, Plk1 overexpression, another member of the polo-like kinase family, has been demonstrated to trigger anoikis resistance through regulation of β-catenin expression, by directly binding to the NF-kB subunit RelA, which inhibits the ubiquitination and degradation of β-catenin [68].