CDK1 and head and neck cancer: To begin determining whether HPV+ head and neck cancer cells are sensitive to roscovitine due to specific CDK inhibition, we assessed the response of HPV-positive and HPV-negative cells to another broad CDK inhibitor, flavopiridol [37, 38], as well as to specific CDK1/2 [39] and CDK4/6 [40] inhibitors.