PLK1 and cancer: In another study, p53 has been suggested as an in vitro predictive biomarker for the Plk1 inhibitor, GSK461364A, with the loss of p53 function resulting in sensitivity to the drug in a panel of human cancer cell lines.69 However, a separate study on colon cancer cell lines with volasertib showed no similar relationship.70 Clearly, the relationship between Plk1 and p53 is complex and further work is required to elucidate the full mechanism of their interaction in different malignancies.