Several small-molecule inhibitors have been developed that have enabled cell biologists to advance our understanding of Plk1 biology, and helped collaborating industry partners to develop Plk1 inhibition as an attractive therapeutic concept based on very efficient tumor cell killing and—in contrast to microtubule-targeting antimitotic agents—specificity for proliferating versus non-proliferating cells (Steegmaier et al, 2007; Taylor & Peters, 2008). This evidence concerns the gene PLK1 and neoplasm.