PLK1 and head and neck squamous cell carcinoma: To explore the cellular effects of PLK1 inhibition on HNSCC and precancer mucosal cells, UM-SCC-22A and VU-preSCC-M3 were exposed to BI6727 (0.25 μM) or GSK461364 (0.07 μM) and after 24 hours cell cycle profiles were analyzed using flow cytometry.