Since the first reports of PLK1 downregulation with anti-sense oligonucleotides and small interfering RNA inducing growth inhibition in cancer cells [230,231,232] and in living animals [27,232] a plethora of studies have been performed focusing on PLK1 inhibitors suitable as anti-cancer drug [233,234,235,236,237] reviewed by [238,239,240]. This evidence concerns the gene PLK1 and cancer.