PLK1 and cancer: In the presence of DNA damages, ATM and ATR mediate phosphorylation and degradation of Bora, which will inhibit PLK1 activity.259 Moreover, PLK1 is also implicated in HR process,260,261 epithelial to mesenchymal transition (EMT),262 autophagy,263 apoptosis264 and even inflammatory response.265 These versatile functions are closely related to cancer initiation and progress, which make PLK1 an attractive target for cancer treatment.266 Two strategies have arisen for the development of PLK1 inhibitors, either targeting PBD domain or kinase domain.