ATM and infection: Consistent with our previous study, TMZ–POH upregulated some DNA damage-related proteins, including phosphorylated ataxia telangiectasia mutated (ATM) and checkpoint kinases 1 and 2 (ChK1/2), and also all those proteins were elevated more significantly under MGMT inhibition by O6-BG in A549 cells (Fig. 3c), but were restored under Ad-MGMT infection in H520 cells (Fig. 3d), suggesting MGMT was involved in TMZ–POH-induced DNA damage.