The combination of AC-1215 and the WEE1 G2 checkpoint kinase (WEE1) inhibitor adavosertib (Adv) suppressed checkpoint kinase 1 (Chk1) activity, which synergistically enhanced the apoptosis in head and neck squamous cell carcinoma (HNSCC) cells via mitotic catastrophe in a p53-dependent manner in [63]. Here, CHEK1 is linked to head and neck squamous cell carcinoma.