Given that PLK1 is often overexpressed in a broad spectrum of cancers, with highest expression levels being correlated with poor prognosis in several cancer types [10–13], we further validated the HTS result with the second-generation PLK1 inhibitor volasertib (BI6727, Boehringer Ingelheim, Germany) as a single agent and in combination with ionizing radiation (IR). The gene discussed is PLK1; the disease is cancer.