For another member of the PLK family, PLK4, was demonstrated that haploinsufficient Plk4 + /- mice have a higher incidence of liver and lung cancer, which was due to an impaired regulation of Cyclins D1, E and B1 and of CDK1 supporting a critical role of polo-like kinases for tissue homeostasis62. The gene discussed is CCND1; the disease is lung carcinoma.