CHEK1 and oral cavity squamous cell carcinoma: It has been reported that inhibition the ATR-CHEK1 pathway could enhance the efficacy of DNA damage agents in variety of carcinomas, ciplastin in CRC, gemcitabine in pancreatic cancer [45] and cytosine arabinoside in Refractory Acute Leukemias [46], and reverse the radioresistance in oral squamous cell carcinoma cells [47].