CHEK1 and rectal cancer: Based on the known roles of Chk1/2 and p53 in the DNA damage response pathway and the preferential effects of Chk1/2 knockdown and inhibitors (including AZD7762) in cells with deficient versus proficient p53 [25,42], rectal cancers with compromised p53 may be more readily radiosensitized by AZD7762.