The combination of niraparib and the Chk1 inhibitor MK-8776 further enhanced the radiosensitivity of HPV-positive HNSCC cells, whereas the combination of niraparib and the Wee1 inhibitor MK-1775 significantly increased the radiosensitivity of HPV-negative HNSCC cells (111). Here, CHEK1 is linked to head and neck squamous cell carcinoma.