The serine/threonine protein kinase PLK2 (polo-like kinase) encoded by the PLK2 gene, which can also be induced by p53, acts as a putative tumor suppressor by interacting with signaling molecules involved in antitumor activity, while the dysregulation of PLK2 in some types of cancer results in tumor-promoting effects (see [37] and refs. therein). This evidence concerns the gene PLK2 and cancer.