Taking in vitro studies of lung cancer for example, the Chk1 inhibitor UCN-01 [82], Wee1 inhibitor AZD1775 [83], ATR inhibitor VX-970 [84] in combination with cytotoxic agents (irradiation or cisplatin) have been shown to selectively target p53-deficient lung cancer cells, demonstrated using otherwise isogenic p53MUT and p53WT paired cell systems. Here, CHEK1 is linked to lung cancer.