ATR and malignant colon neoplasm: In colon cancer cells, MLH1 requires ATR (Stojic et al, 2004) and ATM (Adamson et al, 2005) to phosphorylate H2AX and to signal cell cycle arrest, but does not require WT p53 for either process (Cejka et al, 2003); however, MLH1 does require p53 to mediate an autophagic response to 6TG (Zeng et al, 2007).