PLK1 and cancer: Given the important roles of PLK1 for chromosome segregation and centromere maintenance, it is not surprising that it is highly upregulated in human tumors9 and is considered as a prime therapeutic target.10 Various potent small molecule inhibitors have been developed against PLK1 and have shown promise in clinical trials.10 However, in light of our recent finding of PLK1 in centromere integrity maintenance, the use of PLK1 inhibitors in cancer therapies may need to be re-visited.