PLK1 and neoplasm: A study by Lilia Gheghiani provides in vivo proof that abnormal expression of PLK1 triggers the overriding of cell cycle checkpoints to drive tumorigenesis and chromosomal instability and that high expression levels of PLK1 are always correlated with poorer patient prognosis and are related to high tumour grade, which strongly indicates that PLK1 plays key roles in tumour progression and initiation [12, 16, 17].